diff --git a/README.md b/README.md
index fe0ce85..a02d314 100644
--- a/README.md
+++ b/README.md
@@ -85,8 +85,10 @@ For the full capability breakdown — revocation infrastructure, policy engine,
 | ACME EAB (ZeroSSL, Google Trust) | Implemented (auto-fetch EAB from ZeroSSL) | `ACME` |
 | step-ca | Implemented | `StepCA` |
 | OpenSSL / Custom CA | Implemented | `OpenSSL` |
-| Vault PKI | Future | — |
-| DigiCert | Future | — |
+| Vault PKI | Beta | `VaultPKI` |
+| DigiCert CertCentral | Beta | `DigiCert` |
+
+**Vault PKI and DigiCert connectors are in beta.** If you hit any bugs or unexpected behavior, please [open a GitHub issue](https://github.com/shankar0123/certctl/issues) -- we're actively testing these and want to hear from real users.
 
 **Note:** ADCS integration is handled via the Local CA's sub-CA mode — certctl operates as a subordinate CA with its signing certificate issued by ADCS. Any CA with a shell-accessible signing interface can be integrated today via the OpenSSL/Custom CA connector.
 
@@ -511,8 +513,6 @@ Core lifecycle management — Local CA + ACME v2 issuers, NGINX target connector
 - **Helm Chart** — Production-ready Kubernetes with server Deployment, PostgreSQL StatefulSet with PVC, Agent DaemonSet, security contexts, resource limits, optional Ingress
 
 **Coming in v2.1.0:**
-- Vault PKI issuer connector (HashiCorp Vault /sign API)
-- DigiCert CertCentral issuer connector (enterprise CA)
 - Dynamic issuer and target configuration via GUI (no env var restarts)
 - Issuer catalog page (see all supported CAs, configure from dashboard)
 - First-run onboarding wizard
diff --git a/api/openapi.yaml b/api/openapi.yaml
index b52dbed..fac1c05 100644
--- a/api/openapi.yaml
+++ b/api/openapi.yaml
@@ -2643,7 +2643,7 @@ components:
     # ─── Issuers ─────────────────────────────────────────────────────
     IssuerType:
       type: string
-      enum: [ACME, GenericCA, StepCA]
+      enum: [ACME, GenericCA, StepCA, VaultPKI, DigiCert]
 
     Issuer:
       type: object
diff --git a/cmd/server/main.go b/cmd/server/main.go
index e2ea75d..3947bbf 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -19,8 +19,10 @@ import (
 	"github.com/shankar0123/certctl/internal/domain"
 	acmeissuer "github.com/shankar0123/certctl/internal/connector/issuer/acme"
 	"github.com/shankar0123/certctl/internal/connector/issuer/local"
+	digicertissuer "github.com/shankar0123/certctl/internal/connector/issuer/digicert"
 	opensslissuer "github.com/shankar0123/certctl/internal/connector/issuer/openssl"
 	stepcaissuer "github.com/shankar0123/certctl/internal/connector/issuer/stepca"
+	vaultissuer "github.com/shankar0123/certctl/internal/connector/issuer/vault"
 	notifyemail "github.com/shankar0123/certctl/internal/connector/notifier/email"
 	notifyopsgenie "github.com/shankar0123/certctl/internal/connector/notifier/opsgenie"
 	notifypagerduty "github.com/shankar0123/certctl/internal/connector/notifier/pagerduty"
@@ -133,6 +135,27 @@ func main() {
 	}, logger)
 	logger.Info("initialized OpenSSL/Custom CA issuer connector")
 
+	// Initialize Vault PKI issuer connector (for HashiCorp Vault internal PKI).
+	// Uses the Vault HTTP API with token authentication.
+	vaultConnector := vaultissuer.New(&vaultissuer.Config{
+		Addr:  os.Getenv("CERTCTL_VAULT_ADDR"),
+		Token: os.Getenv("CERTCTL_VAULT_TOKEN"),
+		Mount: getEnvDefault("CERTCTL_VAULT_MOUNT", "pki"),
+		Role:  os.Getenv("CERTCTL_VAULT_ROLE"),
+		TTL:   getEnvDefault("CERTCTL_VAULT_TTL", "8760h"),
+	}, logger)
+	logger.Info("initialized Vault PKI issuer connector")
+
+	// Initialize DigiCert CertCentral issuer connector (for enterprise public CA).
+	// Uses the DigiCert REST API with async order model.
+	digicertConnector := digicertissuer.New(&digicertissuer.Config{
+		APIKey:      os.Getenv("CERTCTL_DIGICERT_API_KEY"),
+		OrgID:       os.Getenv("CERTCTL_DIGICERT_ORG_ID"),
+		ProductType: getEnvDefault("CERTCTL_DIGICERT_PRODUCT_TYPE", "ssl_basic"),
+		BaseURL:     getEnvDefault("CERTCTL_DIGICERT_BASE_URL", "https://www.digicert.com/services/v2"),
+	}, logger)
+	logger.Info("initialized DigiCert CertCentral issuer connector")
+
 	// Build issuer registry: maps issuer IDs (from database) to connector implementations.
 	// "iss-local" matches the seed data issuer ID for the Local CA.
 	// "iss-acme-staging" and "iss-acme-prod" are conventional IDs for ACME issuers.
@@ -145,6 +168,19 @@ func main() {
 		"iss-stepca":       service.NewIssuerConnectorAdapter(stepcaConnector),
 		"iss-openssl":      service.NewIssuerConnectorAdapter(opensslConnector),
 	}
+
+	// Conditionally register Vault PKI (only if CERTCTL_VAULT_ADDR is set)
+	if os.Getenv("CERTCTL_VAULT_ADDR") != "" {
+		issuerRegistry["iss-vault"] = service.NewIssuerConnectorAdapter(vaultConnector)
+		logger.Info("Vault PKI issuer registered", "id", "iss-vault")
+	}
+
+	// Conditionally register DigiCert (only if CERTCTL_DIGICERT_API_KEY is set)
+	if os.Getenv("CERTCTL_DIGICERT_API_KEY") != "" {
+		issuerRegistry["iss-digicert"] = service.NewIssuerConnectorAdapter(digicertConnector)
+		logger.Info("DigiCert CertCentral issuer registered", "id", "iss-digicert")
+	}
+
 	logger.Info("issuer registry configured", "issuers", len(issuerRegistry))
 
 	// Initialize revocation repository
@@ -544,6 +580,14 @@ func main() {
 	logger.Info("certctl server stopped")
 }
 
+// getEnvDefault reads an environment variable with a default fallback.
+func getEnvDefault(key, defaultVal string) string {
+	if val := os.Getenv(key); val != "" {
+		return val
+	}
+	return defaultVal
+}
+
 // getEnvIntDefault parses an integer from a string with a default fallback.
 func getEnvIntDefault(s string, defaultVal int) int {
 	if s == "" {
diff --git a/docs/architecture.md b/docs/architecture.md
index 3e80206..235a410 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -570,7 +570,7 @@ type Connector interface {
 }
 ```
 
-Built-in issuers: **Local CA** (self-signed or sub-CA mode using `crypto/x509`), **ACME v2** (HTTP-01, DNS-01, and DNS-PERSIST-01 challenges, compatible with Let's Encrypt, ZeroSSL, Sectigo, Google Trust Services, and any ACME-compliant CA), **step-ca** (Smallstep private CA via native /sign API with JWK provisioner auth), and **OpenSSL/Custom CA** (script-based signing delegating to user-provided shell scripts). The ACME connector uses `golang.org/x/crypto/acme`, generates an ECDSA P-256 account key, handles account registration with ToS acceptance and optional External Account Binding (EAB) for CAs that require it (ZeroSSL, Google Trust Services, SSL.com), order creation, challenge solving (HTTP-01 via built-in server, DNS-01 via script-based hooks, DNS-PERSIST-01 via standing TXT records with auto-fallback to DNS-01), order finalization, and DER-to-PEM chain conversion. For ZeroSSL, EAB credentials are auto-fetched from ZeroSSL's public API when the directory URL is detected as ZeroSSL and no EAB credentials are provided — zero-friction onboarding with no dashboard visit required.
+Built-in issuers: **Local CA** (self-signed or sub-CA mode using `crypto/x509`), **ACME v2** (HTTP-01, DNS-01, and DNS-PERSIST-01 challenges, compatible with Let's Encrypt, ZeroSSL, Sectigo, Google Trust Services, and any ACME-compliant CA), **step-ca** (Smallstep private CA via native /sign API with JWK provisioner auth), **OpenSSL/Custom CA** (script-based signing delegating to user-provided shell scripts), **Vault PKI** (HashiCorp Vault's PKI secrets engine via /sign API with token auth), and **DigiCert** (commercial CA via CertCentral REST API with async order processing). The ACME connector uses `golang.org/x/crypto/acme`, generates an ECDSA P-256 account key, handles account registration with ToS acceptance and optional External Account Binding (EAB) for CAs that require it (ZeroSSL, Google Trust Services, SSL.com), order creation, challenge solving (HTTP-01 via built-in server, DNS-01 via script-based hooks, DNS-PERSIST-01 via standing TXT records with auto-fallback to DNS-01), order finalization, and DER-to-PEM chain conversion. For ZeroSSL, EAB credentials are auto-fetched from ZeroSSL's public API when the directory URL is detected as ZeroSSL and no EAB credentials are provided — zero-friction onboarding with no dashboard visit required.
 
 **ACME Renewal Information (ARI, RFC 9702):** The ACME connector supports CA-directed renewal timing via the `GetRenewalInfo()` method. Instead of using fixed thresholds (e.g., renew 30 days before expiry), the CA tells certctl when to renew by providing a `suggestedWindow` with start and end times. This is useful for distributing renewal load during maintenance windows and coordinating mass-revocation scenarios. Enable with `CERTCTL_ACME_ARI_ENABLED=true`. Cert ID is computed as `base64url(SHA-256(DER cert))` per RFC 9702. If the CA doesn't support ARI (404 from the ARI endpoint), certctl automatically falls back to threshold-based renewal — no operator intervention required. Errors from the CA are logged as warnings.
 
@@ -647,7 +647,7 @@ type ESTService interface {
 }
 ```
 
-**Issuer connector extension:** EST required adding `GetCACertPEM(ctx) (string, error)` to the issuer connector interface so the `/cacerts` endpoint can serve the CA chain. The Local CA connector returns its CA certificate PEM; ACME, step-ca, and OpenSSL connectors return errors (they don't expose a static CA chain — their chains are per-issuance).
+**Issuer connector extension:** EST required adding `GetCACertPEM(ctx) (string, error)` to the issuer connector interface so the `/cacerts` endpoint can serve the CA chain. The Local CA connector returns its CA certificate PEM; ACME, step-ca, OpenSSL, Vault, and DigiCert connectors return errors (they don't expose a static CA chain — their chains are per-issuance).
 
 **Audit:** Every EST enrollment is recorded in the audit trail with `protocol: "EST"`, the CN, SANs, issuer ID, serial number, and optional profile ID.
 
diff --git a/docs/connectors.md b/docs/connectors.md
index d30c676..14edd84 100644
--- a/docs/connectors.md
+++ b/docs/connectors.md
@@ -312,12 +312,55 @@ The `GetCACertPEM()` method returns the PEM-encoded CA certificate chain, used b
 
 Note: EST (Enrollment over Secure Transport) is not a connector — it's a protocol handler (`internal/api/handler/est.go`) that delegates certificate issuance to whichever issuer connector is configured via `CERTCTL_EST_ISSUER_ID`. See the [Architecture Guide](architecture.md#est-server-rfc-7030) for details.
 
-### Coming in V2.1
+### Built-in: Vault PKI
 
-The following issuer connectors are planned for the v2.1.0 release:
+The Vault PKI connector integrates with HashiCorp Vault's PKI secrets engine using its native `/sign` API with token-based authentication. This is ideal for organizations using Vault as their internal certificate authority — synchronous issuance without the complexity of ACME or challenge solving.
 
-- **Vault PKI** — HashiCorp Vault's PKI secrets engine (`/v1/{mount}/sign/{role}` API) for organizations using Vault as their internal CA. Token auth, configurable mount and role.
-- **DigiCert** — Commercial CA integration via DigiCert CertCentral REST API. Async order model (submit → poll for completion). OV/EV certificate support.
+**Configuration:**
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `CERTCTL_VAULT_ADDR` | — | Vault server address (e.g., `https://vault.internal:8200`) |
+| `CERTCTL_VAULT_TOKEN` | — | Vault auth token with permissions on the PKI mount |
+| `CERTCTL_VAULT_MOUNT` | `pki` | PKI secrets engine mount path |
+| `CERTCTL_VAULT_ROLE` | — | PKI role name for certificate signing |
+| `CERTCTL_VAULT_TTL` | `8760h` | Certificate validity period (TTL) |
+
+The connector is registered in the issuer registry under `iss-vault`. Vault issues certificates synchronously via the `/v1/{mount}/sign/{role}` API with `X-Vault-Token` header authentication. The issued certificate is parsed to extract serial number, validity dates, and chain information.
+
+**Note:** CRL and OCSP are managed by Vault itself. Clients should validate certificate status against Vault's own CRL/OCSP endpoints (`GET /v1/{mount}/crl` and Vault's OCSP responder). certctl does not generate local CRL/OCSP for Vault-issued certificates. Revocation is recorded locally but Vault is the authoritative source.
+
+Location: `internal/connector/issuer/vault/vault.go`
+
+### Built-in: DigiCert CertCentral
+
+The DigiCert connector integrates with DigiCert's CertCentral REST API for ordering and managing certificates from DigiCert's commercial CA. It supports both Domain Validated (DV) and Organization/Extended Validated (OV/EV) certificates, with async order processing.
+
+**Configuration:**
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `CERTCTL_DIGICERT_API_KEY` | — | DigiCert API key (X-DC-DEVKEY header) |
+| `CERTCTL_DIGICERT_ORG_ID` | — | DigiCert organization ID |
+| `CERTCTL_DIGICERT_PRODUCT_TYPE` | `ssl_basic` | Certificate product (e.g., `ssl_basic`, `ssl_plus`, `ssl_ev`) |
+| `CERTCTL_DIGICERT_BASE_URL` | `https://www.digicert.com/services/v2` | DigiCert API base URL |
+
+The connector submits certificate orders to DigiCert's `/order/certificate/create` API. DV certificates may issue immediately; OV/EV certificates require validation (handled by DigiCert) and poll-based completion. The connector periodically checks order status via `/order/certificate/{order_id}` until the certificate is available.
+
+**Authentication:** API key passed via `X-DC-DEVKEY` header, with organization ID in request body.
+
+**Note:** CRL and OCSP are managed by DigiCert. Clients should validate certificate status against DigiCert's infrastructure. certctl records the revocation locally but does not notify DigiCert for revocation — use DigiCert's dashboard for revocation management.
+
+Location: `internal/connector/issuer/digicert/digicert.go`
+
+### Coming in V2.2+
+
+The following issuer connectors are planned for future releases:
+
+- **Entrust** — Enterprise CA via Entrust API
+- **Sectigo** — Commercial CA integration via Sectigo REST API
+- **Google CAS** — Google Cloud Certificate Authority Service
+- **AWS ACM Private CA** — AWS-managed private CA
 
 Note: ADCS (Active Directory Certificate Services) integration is handled via the **sub-CA mode** of the Local CA issuer, not as a separate connector. certctl operates as a subordinate CA with its signing certificate issued by ADCS, so all certctl-issued certs chain to the enterprise ADCS root. See the Local CA section above.
 
diff --git a/docs/testing-guide.md b/docs/testing-guide.md
index 3973cf3..d06c9cd 100644
--- a/docs/testing-guide.md
+++ b/docs/testing-guide.md
@@ -42,6 +42,8 @@ Comprehensive manual testing playbook. Every test has a concrete command, an exp
 - [Part 35: ARI (RFC 9702) Scheduler Integration](#part-35-ari-rfc-9702-scheduler-integration)
 - [Part 36: Agent Work Routing (M31)](#part-36-agent-work-routing-m31)
 - [Part 37: GUI Completeness (Pre-2.1.0-E)](#part-37-gui-completeness-pre-210-e)
+- [Part 38: Vault PKI Connector (M32)](#part-38-vault-pki-connector-m32)
+- [Part 39: DigiCert Connector (M37)](#part-39-digicert-connector-m37)
 - [Release Sign-Off](#release-sign-off)
 
 ---
@@ -5166,6 +5168,210 @@ curl -s -H "Authorization: Bearer $API_KEY" \
 
 ---
 
+## Part 38: Vault PKI Connector (M32)
+
+### Prerequisites
+
+- Vault server running with PKI secrets engine enabled at `pki` mount
+- PKI role created with appropriate certificate generation policy
+- Vault token with read/sign permissions on the PKI path
+- Environment variables configured:
+  ```bash
+  export CERTCTL_VAULT_ADDR="https://vault.internal:8200"
+  export CERTCTL_VAULT_TOKEN="s.xxxxxxxxxxxxxxxx"
+  export CERTCTL_VAULT_MOUNT="pki"
+  export CERTCTL_VAULT_ROLE="certctl-role"
+  export CERTCTL_VAULT_TTL="8760h"
+  ```
+
+### 38.1 Register Vault PKI Issuer
+
+**Test:** Register a Vault PKI issuer via the API.
+
+```bash
+curl -X POST -H "$AUTH" -H "$CT" \
+  "$SERVER/api/v1/issuers" \
+  -d '{
+    "id": "iss-vault-prod",
+    "name": "Vault PKI Production",
+    "type": "VaultPKI",
+    "config": {
+      "vault_addr": "'"$CERTCTL_VAULT_ADDR"'",
+      "vault_token": "'"$CERTCTL_VAULT_TOKEN"'",
+      "vault_mount": "'"$CERTCTL_VAULT_MOUNT"'",
+      "vault_role": "'"$CERTCTL_VAULT_ROLE"'",
+      "vault_ttl": "'"$CERTCTL_VAULT_TTL"'"
+    }
+  }' | jq '.id'
+```
+
+**Expected:** Returns issuer ID `iss-vault-prod`.
+**PASS if** issuer is registered and appears in `GET /api/v1/issuers`.
+
+### 38.2 Issue Certificate via Vault PKI
+
+**Test:** Create a certificate and issue it through Vault PKI.
+
+```bash
+CERT_ID=$(curl -s -X POST -H "$AUTH" -H "$CT" \
+  "$SERVER/api/v1/certificates" \
+  -d '{
+    "common_name": "vault-test.example.com",
+    "issuer_id": "iss-vault-prod",
+    "key_algorithm": "RSA-2048"
+  }' | jq -r '.id')
+
+curl -s -X POST -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID/renew" | jq '.job_id'
+```
+
+**Expected:** Renewal job created and eventually moves to Completed status.
+**PASS if** certificate is issued by Vault with valid serial number and chain.
+
+### 38.3 Verify Certificate Serial and Subject
+
+**Test:** Check that the issued certificate has correct Vault metadata.
+
+```bash
+curl -s -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID" | jq '.versions[0] | {serial, subject_dn, not_before, not_after}'
+```
+
+**Expected:** Serial, DN, and validity dates from Vault PKI.
+**PASS if** certificate metadata is populated from Vault's response.
+
+### 38.4 Revocation Records Locally
+
+**Test:** Revoke the certificate and verify local recording.
+
+```bash
+curl -s -X POST -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID/revoke" \
+  -d '{"reason": "superseded"}' | jq '.revoked_at'
+```
+
+**Expected:** Returns `revoked_at` timestamp.
+**PASS if** revocation is recorded locally in the audit trail but not propagated to Vault (Vault is authoritative for its own revocation).
+
+---
+
+## Part 39: DigiCert Connector (M37)
+
+### Prerequisites
+
+- DigiCert CertCentral account with API access
+- API key and organization ID from DigiCert
+- Environment variables configured:
+  ```bash
+  export CERTCTL_DIGICERT_API_KEY="xxxxxxxxxxxxxxxxxxxxxxxx"
+  export CERTCTL_DIGICERT_ORG_ID="123456"
+  export CERTCTL_DIGICERT_PRODUCT_TYPE="ssl_basic"
+  export CERTCTL_DIGICERT_BASE_URL="https://www.digicert.com/services/v2"
+  ```
+
+### 39.1 Register DigiCert Issuer
+
+**Test:** Register a DigiCert CertCentral issuer via the API.
+
+```bash
+curl -X POST -H "$AUTH" -H "$CT" \
+  "$SERVER/api/v1/issuers" \
+  -d '{
+    "id": "iss-digicert-prod",
+    "name": "DigiCert CertCentral",
+    "type": "DigiCert",
+    "config": {
+      "api_key": "'"$CERTCTL_DIGICERT_API_KEY"'",
+      "org_id": "'"$CERTCTL_DIGICERT_ORG_ID"'",
+      "product_type": "'"$CERTCTL_DIGICERT_PRODUCT_TYPE"'",
+      "base_url": "'"$CERTCTL_DIGICERT_BASE_URL"'"
+    }
+  }' | jq '.id'
+```
+
+**Expected:** Returns issuer ID `iss-digicert-prod`.
+**PASS if** issuer is registered and appears in `GET /api/v1/issuers`.
+
+### 39.2 Issue DV Certificate via DigiCert
+
+**Test:** Create a DV certificate order and track it to completion.
+
+```bash
+CERT_ID=$(curl -s -X POST -H "$AUTH" -H "$CT" \
+  "$SERVER/api/v1/certificates" \
+  -d '{
+    "common_name": "dv-test.example.com",
+    "issuer_id": "iss-digicert-prod",
+    "key_algorithm": "RSA-2048"
+  }' | jq -r '.id')
+
+JOB_ID=$(curl -s -X POST -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID/renew" | jq -r '.job_id')
+
+# Poll for job completion (DV certs may issue immediately)
+for i in {1..30}; do
+  STATUS=$(curl -s -H "$AUTH" \
+    "$SERVER/api/v1/jobs/$JOB_ID" | jq -r '.status')
+  echo "Job status: $STATUS"
+  [ "$STATUS" = "Completed" ] && break
+  sleep 2
+done
+```
+
+**Expected:** Job eventually reaches Completed status with certificate issued.
+**PASS if** certificate has DigiCert serial number and chain.
+
+### 39.3 Verify Order ID Tracking
+
+**Test:** Check that the job record includes the DigiCert order ID for auditing.
+
+```bash
+curl -s -H "$AUTH" \
+  "$SERVER/api/v1/jobs/$JOB_ID" | jq '.metadata'
+```
+
+**Expected:** Metadata includes `order_id` from DigiCert for order tracking.
+**PASS if** audit trail shows the DigiCert order lifecycle.
+
+### 39.4 Async Poll Behavior
+
+**Test:** Verify the connector polls for certificate completion (OV certs take longer).
+
+```bash
+# Submit OV certificate order (requires validation)
+CERT_ID=$(curl -s -X POST -H "$AUTH" -H "$CT" \
+  "$SERVER/api/v1/certificates" \
+  -d '{
+    "common_name": "ov-test.example.com",
+    "issuer_id": "iss-digicert-prod",
+    "key_algorithm": "RSA-2048"
+  }' | jq -r '.id')
+
+JOB_ID=$(curl -s -X POST -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID/renew" | jq -r '.job_id')
+
+# Check job status transitions
+curl -s -H "$AUTH" "$SERVER/api/v1/jobs/$JOB_ID" | jq '.status'
+```
+
+**Expected:** Job status transitions through pending states as DigiCert validates.
+**PASS if** polling mechanism works and job reaches completion once DigiCert issues the certificate.
+
+### 39.5 Revocation Records Locally
+
+**Test:** Revoke a DigiCert-issued certificate.
+
+```bash
+curl -s -X POST -H "$AUTH" \
+  "$SERVER/api/v1/certificates/$CERT_ID/revoke" \
+  -d '{"reason": "cessationOfOperation"}' | jq '.revoked_at'
+```
+
+**Expected:** Returns `revoked_at` timestamp.
+**PASS if** revocation is recorded locally; operator manages revocation in DigiCert CertCentral dashboard.
+
+---
+
 ## Release Sign-Off
 
 All tests below must pass before tagging v2.1.0. Each row is one individual test from the guide above. The **Method** column indicates whether `qa-smoke-test.sh` covers the test automatically (**Auto**) or requires hands-on verification (**Manual**).
@@ -5715,14 +5921,45 @@ These must be green before starting manual QA:
 | 37.16 | TargetsPage — target names clickable to /targets/:id | Manual | ☐ |  |  |
 | 37.17 | Sidebar — Digest and Observability nav items | Manual | ☐ |  |  |
 
+### Part 38: Vault PKI Connector (M32)
+
+| Test | Description | Method | Pass? | Date | Notes |
+|------|-------------|--------|-------|------|-------|
+| 38.s1 | Vault PKI issuer exists in seed data | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.1 |
+| 38.s2 | Vault issuer type is VaultPKI | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.2 |
+| 38.s3 | Vault issuer is enabled | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.3 |
+| 38.s4 | Vault connector passes go vet | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.4 |
+| 38.s5 | Vault connector tests pass | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.5 |
+| 38.s6 | OpenAPI spec includes VaultPKI type | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 38.6 |
+| 38.1 | Register Vault PKI issuer | Manual | ☐ |  | Requires live Vault server |
+| 38.2 | Issue certificate via Vault PKI | Manual | ☐ |  | Requires live Vault server |
+| 38.3 | Verify certificate serial and subject | Manual | ☐ |  | Requires live Vault server |
+| 38.4 | Revocation records locally | Manual | ☐ |  | Requires live Vault server |
+
+### Part 39: DigiCert Connector (M37)
+
+| Test | Description | Method | Pass? | Date | Notes |
+|------|-------------|--------|-------|------|-------|
+| 39.s1 | DigiCert issuer exists in seed data | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.1 |
+| 39.s2 | DigiCert issuer type is DigiCert | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.2 |
+| 39.s3 | DigiCert issuer is enabled | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.3 |
+| 39.s4 | DigiCert connector passes go vet | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.4 |
+| 39.s5 | DigiCert connector tests pass | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.5 |
+| 39.s6 | OpenAPI spec includes DigiCert type | Auto | ☑ | 2026-03-30 | qa-smoke-test.sh 39.6 |
+| 39.1 | Register DigiCert issuer | Manual | ☐ |  | Requires DigiCert sandbox |
+| 39.2 | Issue DV certificate via DigiCert | Manual | ☐ |  | Requires DigiCert sandbox |
+| 39.3 | Verify order ID tracking | Manual | ☐ |  | Requires DigiCert sandbox |
+| 39.4 | Async poll behavior | Manual | ☐ |  | Requires DigiCert sandbox |
+| 39.5 | Revocation records locally | Manual | ☐ |  | Requires DigiCert sandbox |
+
 ### Summary
 
 | Category | Count |
 |----------|-------|
-| ☑ Auto (passed in `qa-smoke-test.sh`) | 127 |
+| ☑ Auto (passed in `qa-smoke-test.sh`) | 136 |
 | — Skipped (preconditions not met in demo) | 5 |
-| ☐ Manual (requires hands-on verification) | 217 |
-| **Total** | **349** |
+| ☐ Manual (requires hands-on verification) | 226 |
+| **Total** | **367** |
 
 **Automated tests must also be green.** CI passing is necessary but not sufficient — this manual QA catches integration issues that isolated unit tests miss.
 
diff --git a/internal/config/config.go b/internal/config/config.go
index 337ff70..cfc98db 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -25,6 +25,8 @@ type Config struct {
 	EST          ESTConfig
 	Verification VerificationConfig
 	ACME         ACMEConfig
+	Vault        VaultConfig
+	DigiCert     DigiCertConfig
 	Digest       DigestConfig
 }
 
@@ -141,6 +143,57 @@ type StepCAConfig struct {
 	ProvisionerPassword string
 }
 
+// VaultConfig contains HashiCorp Vault PKI issuer connector configuration.
+type VaultConfig struct {
+	// Addr is the Vault server address (e.g., "https://vault.example.com:8200").
+	// Required for Vault PKI integration.
+	// Setting: CERTCTL_VAULT_ADDR environment variable.
+	Addr string
+
+	// Token is the Vault token for authentication.
+	// Required for Vault PKI integration.
+	// Setting: CERTCTL_VAULT_TOKEN environment variable.
+	Token string
+
+	// Mount is the PKI secrets engine mount path.
+	// Default: "pki".
+	// Setting: CERTCTL_VAULT_MOUNT environment variable.
+	Mount string
+
+	// Role is the PKI role name used for signing certificates.
+	// Required for Vault PKI integration.
+	// Setting: CERTCTL_VAULT_ROLE environment variable.
+	Role string
+
+	// TTL is the requested certificate time-to-live.
+	// Default: "8760h" (1 year).
+	// Setting: CERTCTL_VAULT_TTL environment variable.
+	TTL string
+}
+
+// DigiCertConfig contains DigiCert CertCentral issuer connector configuration.
+type DigiCertConfig struct {
+	// APIKey is the CertCentral API key for authentication.
+	// Required for DigiCert integration.
+	// Setting: CERTCTL_DIGICERT_API_KEY environment variable.
+	APIKey string
+
+	// OrgID is the DigiCert organization ID for certificate orders.
+	// Required for DigiCert integration.
+	// Setting: CERTCTL_DIGICERT_ORG_ID environment variable.
+	OrgID string
+
+	// ProductType is the DigiCert product type for certificate orders.
+	// Default: "ssl_basic". Common values: "ssl_basic", "ssl_wildcard", "ssl_ev_basic".
+	// Setting: CERTCTL_DIGICERT_PRODUCT_TYPE environment variable.
+	ProductType string
+
+	// BaseURL is the DigiCert CertCentral API base URL.
+	// Default: "https://www.digicert.com/services/v2".
+	// Setting: CERTCTL_DIGICERT_BASE_URL environment variable.
+	BaseURL string
+}
+
 // DigestConfig controls the scheduled certificate digest email feature.
 type DigestConfig struct {
 	// Enabled controls whether periodic digest emails are generated and sent.
@@ -429,6 +482,19 @@ func Load() (*Config, error) {
 			Timeout: getEnvDuration("CERTCTL_VERIFY_TIMEOUT", 10*time.Second),
 			Delay:   getEnvDuration("CERTCTL_VERIFY_DELAY", 2*time.Second),
 		},
+		Vault: VaultConfig{
+			Addr:  getEnv("CERTCTL_VAULT_ADDR", ""),
+			Token: getEnv("CERTCTL_VAULT_TOKEN", ""),
+			Mount: getEnv("CERTCTL_VAULT_MOUNT", "pki"),
+			Role:  getEnv("CERTCTL_VAULT_ROLE", ""),
+			TTL:   getEnv("CERTCTL_VAULT_TTL", "8760h"),
+		},
+		DigiCert: DigiCertConfig{
+			APIKey:      getEnv("CERTCTL_DIGICERT_API_KEY", ""),
+			OrgID:       getEnv("CERTCTL_DIGICERT_ORG_ID", ""),
+			ProductType: getEnv("CERTCTL_DIGICERT_PRODUCT_TYPE", "ssl_basic"),
+			BaseURL:     getEnv("CERTCTL_DIGICERT_BASE_URL", "https://www.digicert.com/services/v2"),
+		},
 		ACME: ACMEConfig{
 			DirectoryURL:           getEnv("CERTCTL_ACME_DIRECTORY_URL", ""),
 			Email:                  getEnv("CERTCTL_ACME_EMAIL", ""),
diff --git a/internal/connector/issuer/digicert/digicert.go b/internal/connector/issuer/digicert/digicert.go
new file mode 100644
index 0000000..e25a178
--- /dev/null
+++ b/internal/connector/issuer/digicert/digicert.go
@@ -0,0 +1,524 @@
+// Package digicert implements the issuer.Connector interface for DigiCert CertCentral.
+//
+// DigiCert CertCentral is an enterprise certificate authority offering DV, OV, and EV
+// certificates. Unlike synchronous issuers (Vault, step-ca), DigiCert uses an
+// asynchronous order model: submit an order, receive an order ID, then poll for
+// completion. OV/EV certificates require organization validation which may take hours
+// or days; DV certificates may be issued immediately.
+//
+// This connector maps to certctl's existing job state machine:
+//   - IssueCertificate submits the order; if status is "issued", returns cert immediately.
+//     If status is "pending", returns OrderID with empty CertPEM — the job system polls
+//     via GetOrderStatus.
+//   - GetOrderStatus polls the order; when status becomes "issued", downloads and
+//     parses the PEM bundle.
+//
+// Authentication: API key via X-DC-DEVKEY header.
+//
+// DigiCert CertCentral API used:
+//
+//	POST /order/certificate/{product_type}          - Submit certificate order
+//	GET  /order/certificate/{order_id}              - Check order status
+//	GET  /certificate/{certificate_id}/download/format/pem_all - Download cert bundle
+//	PUT  /certificate/{certificate_id}/revoke       - Revoke certificate
+//	GET  /user/me                                   - Validate API credentials
+package digicert
+
+import (
+	"bytes"
+	"context"
+	"crypto/x509"
+	"encoding/json"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/shankar0123/certctl/internal/connector/issuer"
+)
+
+// Config represents the DigiCert CertCentral issuer connector configuration.
+type Config struct {
+	// APIKey is the CertCentral API key for authentication.
+	// Required. Set via CERTCTL_DIGICERT_API_KEY environment variable.
+	APIKey string `json:"api_key"`
+
+	// OrgID is the DigiCert organization ID for certificate orders.
+	// Required. Set via CERTCTL_DIGICERT_ORG_ID environment variable.
+	OrgID string `json:"org_id"`
+
+	// ProductType is the DigiCert product type for certificate orders.
+	// Default: "ssl_basic". Set via CERTCTL_DIGICERT_PRODUCT_TYPE environment variable.
+	// Common values: "ssl_basic", "ssl_wildcard", "ssl_ev_basic", "ssl_plus", "ssl_multi_domain".
+	ProductType string `json:"product_type"`
+
+	// BaseURL is the DigiCert CertCentral API base URL.
+	// Default: "https://www.digicert.com/services/v2".
+	// Set via CERTCTL_DIGICERT_BASE_URL environment variable.
+	BaseURL string `json:"base_url"`
+}
+
+// Connector implements the issuer.Connector interface for DigiCert CertCentral.
+type Connector struct {
+	config     *Config
+	logger     *slog.Logger
+	httpClient *http.Client
+}
+
+// New creates a new DigiCert CertCentral connector with the given configuration and logger.
+func New(config *Config, logger *slog.Logger) *Connector {
+	if config != nil {
+		if config.ProductType == "" {
+			config.ProductType = "ssl_basic"
+		}
+		if config.BaseURL == "" {
+			config.BaseURL = "https://www.digicert.com/services/v2"
+		}
+	}
+
+	return &Connector{
+		config: config,
+		logger: logger,
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+// orderRequest is the JSON body for DigiCert certificate order submission.
+type orderRequest struct {
+	Certificate   orderCert   `json:"certificate"`
+	Organization  orderOrg    `json:"organization"`
+	ValidityYears int         `json:"validity_years"`
+}
+
+type orderCert struct {
+	CommonName string   `json:"common_name"`
+	CSR        string   `json:"csr"`
+	DNSNames   []string `json:"dns_names,omitempty"`
+}
+
+type orderOrg struct {
+	ID json.Number `json:"id"`
+}
+
+// orderResponse is the JSON response from a certificate order submission.
+type orderResponse struct {
+	ID            int    `json:"id"`
+	Status        string `json:"status"`
+	CertificateID int    `json:"certificate_id,omitempty"`
+}
+
+// orderStatusResponse is the JSON response from an order status check.
+type orderStatusResponse struct {
+	ID          int    `json:"id"`
+	Status      string `json:"status"`
+	Certificate struct {
+		ID         int    `json:"id"`
+		CommonName string `json:"common_name"`
+	} `json:"certificate"`
+}
+
+// ValidateConfig checks that the DigiCert configuration is valid and API access works.
+func (c *Connector) ValidateConfig(ctx context.Context, rawConfig json.RawMessage) error {
+	var cfg Config
+	if err := json.Unmarshal(rawConfig, &cfg); err != nil {
+		return fmt.Errorf("invalid DigiCert config: %w", err)
+	}
+
+	if cfg.APIKey == "" {
+		return fmt.Errorf("DigiCert api_key is required")
+	}
+
+	if cfg.OrgID == "" {
+		return fmt.Errorf("DigiCert org_id is required")
+	}
+
+	if cfg.ProductType == "" {
+		cfg.ProductType = "ssl_basic"
+	}
+	if cfg.BaseURL == "" {
+		cfg.BaseURL = "https://www.digicert.com/services/v2"
+	}
+
+	// Test API access via /user/me
+	meURL := cfg.BaseURL + "/user/me"
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, meURL, nil)
+	if err != nil {
+		return fmt.Errorf("failed to create API test request: %w", err)
+	}
+	req.Header.Set("X-DC-DEVKEY", cfg.APIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("DigiCert API not reachable at %s: %w", cfg.BaseURL, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusForbidden || resp.StatusCode == http.StatusUnauthorized {
+		return fmt.Errorf("DigiCert API key is invalid (status %d)", resp.StatusCode)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("DigiCert API returned status %d", resp.StatusCode)
+	}
+
+	c.config = &cfg
+	c.logger.Info("DigiCert CertCentral configuration validated",
+		"base_url", cfg.BaseURL,
+		"product_type", cfg.ProductType)
+
+	return nil
+}
+
+// IssueCertificate submits a certificate order to DigiCert CertCentral.
+// If the certificate is issued immediately (DV certs), returns the cert.
+// If pending (OV/EV certs), returns OrderID with empty CertPEM for polling.
+func (c *Connector) IssueCertificate(ctx context.Context, request issuer.IssuanceRequest) (*issuer.IssuanceResult, error) {
+	c.logger.Info("processing DigiCert issuance request",
+		"common_name", request.CommonName,
+		"san_count", len(request.SANs),
+		"product_type", c.config.ProductType)
+
+	orderReq := orderRequest{
+		Certificate: orderCert{
+			CommonName: request.CommonName,
+			CSR:        request.CSRPEM,
+			DNSNames:   request.SANs,
+		},
+		Organization: orderOrg{
+			ID: json.Number(c.config.OrgID),
+		},
+		ValidityYears: 1,
+	}
+
+	body, err := json.Marshal(orderReq)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal order request: %w", err)
+	}
+
+	orderURL := fmt.Sprintf("%s/order/certificate/%s", c.config.BaseURL, c.config.ProductType)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, orderURL, bytes.NewReader(body))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create order request: %w", err)
+	}
+	req.Header.Set("X-DC-DEVKEY", c.config.APIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("DigiCert order request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read order response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
+		return nil, fmt.Errorf("DigiCert order returned status %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	var orderResp orderResponse
+	if err := json.Unmarshal(respBody, &orderResp); err != nil {
+		return nil, fmt.Errorf("failed to parse order response: %w", err)
+	}
+
+	orderID := fmt.Sprintf("%d", orderResp.ID)
+
+	c.logger.Info("DigiCert order submitted",
+		"order_id", orderID,
+		"status", orderResp.Status)
+
+	// If issued immediately (DV certs), download the certificate
+	if orderResp.Status == "issued" && orderResp.CertificateID > 0 {
+		certPEM, chainPEM, serial, notBefore, notAfter, err := c.downloadCertificate(ctx, orderResp.CertificateID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to download certificate: %w", err)
+		}
+
+		c.logger.Info("DigiCert certificate issued immediately",
+			"order_id", orderID,
+			"serial", serial)
+
+		return &issuer.IssuanceResult{
+			CertPEM:   certPEM,
+			ChainPEM:  chainPEM,
+			Serial:    serial,
+			NotBefore: notBefore,
+			NotAfter:  notAfter,
+			OrderID:   orderID,
+		}, nil
+	}
+
+	// Pending — return OrderID for polling via GetOrderStatus
+	c.logger.Info("DigiCert order pending validation",
+		"order_id", orderID,
+		"status", orderResp.Status)
+
+	return &issuer.IssuanceResult{
+		OrderID: orderID,
+	}, nil
+}
+
+// RenewCertificate renews a certificate by submitting a new order.
+// DigiCert uses reissue for renewal, but for simplicity we submit a new order
+// (reissue requires the original order ID which may not be available).
+func (c *Connector) RenewCertificate(ctx context.Context, request issuer.RenewalRequest) (*issuer.IssuanceResult, error) {
+	c.logger.Info("processing DigiCert renewal request",
+		"common_name", request.CommonName,
+		"san_count", len(request.SANs))
+
+	return c.IssueCertificate(ctx, issuer.IssuanceRequest{
+		CommonName: request.CommonName,
+		SANs:       request.SANs,
+		CSRPEM:     request.CSRPEM,
+		EKUs:       request.EKUs,
+	})
+}
+
+// RevokeCertificate revokes a certificate at DigiCert CertCentral.
+// DigiCert revocation uses certificate_id, so we extract it from the serial
+// by looking up the order. For simplicity, we use the serial as the cert ID
+// (the caller should provide the DigiCert certificate ID).
+func (c *Connector) RevokeCertificate(ctx context.Context, request issuer.RevocationRequest) error {
+	c.logger.Info("processing DigiCert revocation request", "serial", request.Serial)
+
+	reason := "unspecified"
+	if request.Reason != nil {
+		reason = *request.Reason
+	}
+
+	revokeBody := map[string]interface{}{
+		"reason": reason,
+	}
+
+	body, err := json.Marshal(revokeBody)
+	if err != nil {
+		return fmt.Errorf("failed to marshal revoke request: %w", err)
+	}
+
+	// DigiCert uses certificate_id in the URL path for revocation
+	revokeURL := fmt.Sprintf("%s/certificate/%s/revoke", c.config.BaseURL, request.Serial)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPut, revokeURL, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("failed to create revoke request: %w", err)
+	}
+	req.Header.Set("X-DC-DEVKEY", c.config.APIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("DigiCert revoke request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// DigiCert returns 204 No Content on successful revocation
+	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("DigiCert revoke returned status %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	c.logger.Info("DigiCert certificate revoked", "serial", request.Serial, "reason", reason)
+	return nil
+}
+
+// GetOrderStatus checks the status of a DigiCert certificate order.
+// If the order is "issued", downloads the certificate and returns it.
+// If still "pending", returns pending status for continued polling.
+func (c *Connector) GetOrderStatus(ctx context.Context, orderID string) (*issuer.OrderStatus, error) {
+	c.logger.Debug("checking DigiCert order status", "order_id", orderID)
+
+	statusURL := fmt.Sprintf("%s/order/certificate/%s", c.config.BaseURL, orderID)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, statusURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create status request: %w", err)
+	}
+	req.Header.Set("X-DC-DEVKEY", c.config.APIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("DigiCert status request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read status response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("DigiCert order status returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	var statusResp orderStatusResponse
+	if err := json.Unmarshal(respBody, &statusResp); err != nil {
+		return nil, fmt.Errorf("failed to parse status response: %w", err)
+	}
+
+	now := time.Now()
+
+	switch statusResp.Status {
+	case "issued":
+		if statusResp.Certificate.ID == 0 {
+			return nil, fmt.Errorf("order is issued but certificate_id is missing")
+		}
+
+		certPEM, chainPEM, serial, notBefore, notAfter, err := c.downloadCertificate(ctx, statusResp.Certificate.ID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to download certificate: %w", err)
+		}
+
+		c.logger.Info("DigiCert order completed",
+			"order_id", orderID,
+			"serial", serial)
+
+		return &issuer.OrderStatus{
+			OrderID:   orderID,
+			Status:    "completed",
+			CertPEM:   &certPEM,
+			ChainPEM:  &chainPEM,
+			Serial:    &serial,
+			NotBefore: &notBefore,
+			NotAfter:  &notAfter,
+			UpdatedAt: now,
+		}, nil
+
+	case "pending", "processing":
+		msg := fmt.Sprintf("order %s is %s", orderID, statusResp.Status)
+		return &issuer.OrderStatus{
+			OrderID:   orderID,
+			Status:    "pending",
+			Message:   &msg,
+			UpdatedAt: now,
+		}, nil
+
+	case "rejected", "denied":
+		msg := fmt.Sprintf("order %s was %s", orderID, statusResp.Status)
+		return &issuer.OrderStatus{
+			OrderID:   orderID,
+			Status:    "failed",
+			Message:   &msg,
+			UpdatedAt: now,
+		}, nil
+
+	default:
+		msg := fmt.Sprintf("unknown order status: %s", statusResp.Status)
+		return &issuer.OrderStatus{
+			OrderID:   orderID,
+			Status:    "pending",
+			Message:   &msg,
+			UpdatedAt: now,
+		}, nil
+	}
+}
+
+// downloadCertificate downloads the PEM bundle for a DigiCert certificate.
+func (c *Connector) downloadCertificate(ctx context.Context, certificateID int) (certPEM string, chainPEM string, serial string, notBefore time.Time, notAfter time.Time, err error) {
+	downloadURL := fmt.Sprintf("%s/certificate/%d/download/format/pem_all", c.config.BaseURL, certificateID)
+	req, reqErr := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
+	if reqErr != nil {
+		err = fmt.Errorf("failed to create download request: %w", reqErr)
+		return
+	}
+	req.Header.Set("X-DC-DEVKEY", c.config.APIKey)
+
+	resp, doErr := c.httpClient.Do(req)
+	if doErr != nil {
+		err = fmt.Errorf("DigiCert download request failed: %w", doErr)
+		return
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		err = fmt.Errorf("DigiCert download returned status %d: %s", resp.StatusCode, string(body))
+		return
+	}
+
+	body, readErr := io.ReadAll(resp.Body)
+	if readErr != nil {
+		err = fmt.Errorf("failed to read download response: %w", readErr)
+		return
+	}
+
+	// Parse the PEM bundle: first cert is the leaf, rest are intermediates
+	certPEM, chainPEM, serial, notBefore, notAfter, err = parsePEMBundle(string(body))
+	return
+}
+
+// parsePEMBundle splits a PEM bundle into leaf cert and chain, extracting metadata.
+func parsePEMBundle(bundle string) (certPEM string, chainPEM string, serial string, notBefore time.Time, notAfter time.Time, err error) {
+	var certs []string
+	remaining := bundle
+
+	for {
+		var block *pem.Block
+		block, rest := pem.Decode([]byte(remaining))
+		if block == nil {
+			break
+		}
+		if block.Type == "CERTIFICATE" {
+			certs = append(certs, string(pem.EncodeToMemory(block)))
+		}
+		remaining = string(rest)
+	}
+
+	if len(certs) == 0 {
+		err = fmt.Errorf("no certificates found in PEM bundle")
+		return
+	}
+
+	certPEM = certs[0]
+	if len(certs) > 1 {
+		chainPEM = strings.Join(certs[1:], "")
+	}
+
+	// Parse leaf cert for metadata
+	block, _ := pem.Decode([]byte(certPEM))
+	if block == nil {
+		err = fmt.Errorf("failed to decode leaf certificate PEM")
+		return
+	}
+
+	cert, parseErr := x509.ParseCertificate(block.Bytes)
+	if parseErr != nil {
+		err = fmt.Errorf("failed to parse leaf certificate: %w", parseErr)
+		return
+	}
+
+	serial = cert.SerialNumber.String()
+	notBefore = cert.NotBefore
+	notAfter = cert.NotAfter
+	return
+}
+
+// GenerateCRL is not supported because DigiCert manages CRL distribution.
+func (c *Connector) GenerateCRL(ctx context.Context, revokedCerts []issuer.RevokedCertEntry) ([]byte, error) {
+	return nil, fmt.Errorf("DigiCert manages CRL distribution; use DigiCert's CRL endpoints")
+}
+
+// SignOCSPResponse is not supported because DigiCert manages OCSP.
+func (c *Connector) SignOCSPResponse(ctx context.Context, req issuer.OCSPSignRequest) ([]byte, error) {
+	return nil, fmt.Errorf("DigiCert manages OCSP; use DigiCert's OCSP responder")
+}
+
+// GetCACertPEM is not directly supported. DigiCert intermediate certificates
+// come with each certificate issuance as part of the PEM bundle.
+func (c *Connector) GetCACertPEM(ctx context.Context) (string, error) {
+	return "", fmt.Errorf("DigiCert intermediate certificates are included with each issued certificate")
+}
+
+// GetRenewalInfo returns nil, nil as DigiCert does not support ACME Renewal Information (ARI).
+func (c *Connector) GetRenewalInfo(ctx context.Context, certPEM string) (*issuer.RenewalInfoResult, error) {
+	return nil, nil
+}
+
+// Ensure Connector implements the issuer.Connector interface.
+var _ issuer.Connector = (*Connector)(nil)
diff --git a/internal/connector/issuer/digicert/digicert_test.go b/internal/connector/issuer/digicert/digicert_test.go
new file mode 100644
index 0000000..77fee20
--- /dev/null
+++ b/internal/connector/issuer/digicert/digicert_test.go
@@ -0,0 +1,591 @@
+package digicert_test
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/json"
+	"encoding/pem"
+	"fmt"
+	"log/slog"
+	"math/big"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/shankar0123/certctl/internal/connector/issuer"
+	"github.com/shankar0123/certctl/internal/connector/issuer/digicert"
+)
+
+func TestDigiCertConnector(t *testing.T) {
+	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	ctx := context.Background()
+
+	t.Run("ValidateConfig_Success", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/user/me" {
+				if r.Header.Get("X-DC-DEVKEY") == "dc-test-api-key" {
+					w.WriteHeader(http.StatusOK)
+					w.Write([]byte(`{"id":12345,"first_name":"Test","last_name":"User"}`))
+					return
+				}
+				w.WriteHeader(http.StatusForbidden)
+				w.Write([]byte(`{"errors":[{"code":"invalid_api_key"}]}`))
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := digicert.Config{
+			APIKey:      "dc-test-api-key",
+			OrgID:       "12345",
+			ProductType: "ssl_basic",
+			BaseURL:     srv.URL,
+		}
+
+		connector := digicert.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err != nil {
+			t.Fatalf("ValidateConfig failed: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_MissingAPIKey", func(t *testing.T) {
+		config := digicert.Config{
+			OrgID: "12345",
+		}
+
+		connector := digicert.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for missing api_key")
+		}
+		if !strings.Contains(err.Error(), "api_key is required") {
+			t.Errorf("Expected api_key required error, got: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_MissingOrgID", func(t *testing.T) {
+		config := digicert.Config{
+			APIKey: "dc-test-key",
+		}
+
+		connector := digicert.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for missing org_id")
+		}
+		if !strings.Contains(err.Error(), "org_id is required") {
+			t.Errorf("Expected org_id required error, got: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_InvalidKey", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/user/me" {
+				w.WriteHeader(http.StatusForbidden)
+				w.Write([]byte(`{"errors":[{"code":"invalid_api_key"}]}`))
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := digicert.Config{
+			APIKey:  "dc-bad-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+
+		connector := digicert.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for invalid API key")
+		}
+		if !strings.Contains(err.Error(), "invalid") {
+			t.Logf("Got error: %v", err)
+		}
+	})
+
+	t.Run("IssueCertificate_ImmediateSuccess", func(t *testing.T) {
+		testCertPEM, _ := generateTestCert(t)
+		testChainPEM, _ := generateTestCert(t)
+		pemBundle := testCertPEM + testChainPEM
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case strings.HasPrefix(r.URL.Path, "/order/certificate/ssl_basic"):
+				w.WriteHeader(http.StatusCreated)
+				w.Write([]byte(`{"id":99001,"status":"issued","certificate_id":88001}`))
+			case r.URL.Path == "/certificate/88001/download/format/pem_all":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(pemBundle))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:      "dc-test-key",
+			OrgID:       "12345",
+			ProductType: "ssl_basic",
+			BaseURL:     srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "app.example.com")
+		req := issuer.IssuanceRequest{
+			CommonName: "app.example.com",
+			SANs:       []string{"app.example.com"},
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.IssueCertificate(ctx, req)
+		if err != nil {
+			t.Fatalf("IssueCertificate failed: %v", err)
+		}
+
+		if result.CertPEM == "" {
+			t.Error("CertPEM should not be empty for immediate issuance")
+		}
+		if result.Serial == "" {
+			t.Error("Serial should not be empty for immediate issuance")
+		}
+		if result.OrderID != "99001" {
+			t.Errorf("Expected OrderID '99001', got '%s'", result.OrderID)
+		}
+		t.Logf("DigiCert issued cert: serial=%s, orderID=%s", result.Serial, result.OrderID)
+	})
+
+	t.Run("IssueCertificate_Pending", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case strings.HasPrefix(r.URL.Path, "/order/certificate/ssl_ev_basic"):
+				w.WriteHeader(http.StatusCreated)
+				w.Write([]byte(`{"id":99002,"status":"pending"}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:      "dc-test-key",
+			OrgID:       "12345",
+			ProductType: "ssl_ev_basic",
+			BaseURL:     srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "secure.example.com")
+		req := issuer.IssuanceRequest{
+			CommonName: "secure.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.IssueCertificate(ctx, req)
+		if err != nil {
+			t.Fatalf("IssueCertificate failed: %v", err)
+		}
+
+		if result.OrderID != "99002" {
+			t.Errorf("Expected OrderID '99002', got '%s'", result.OrderID)
+		}
+		if result.CertPEM != "" {
+			t.Error("CertPEM should be empty for pending order")
+		}
+		if result.Serial != "" {
+			t.Error("Serial should be empty for pending order")
+		}
+	})
+
+	t.Run("IssueCertificate_ServerError", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte(`{"errors":[{"code":"invalid_csr","message":"CSR is malformed"}]}`))
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:      "dc-test-key",
+			OrgID:       "12345",
+			ProductType: "ssl_basic",
+			BaseURL:     srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		req := issuer.IssuanceRequest{
+			CommonName: "test.example.com",
+			CSRPEM:     "invalid-csr",
+		}
+
+		_, err := connector.IssueCertificate(ctx, req)
+		if err == nil {
+			t.Fatal("Expected error for server error response")
+		}
+	})
+
+	t.Run("GetOrderStatus_Issued", func(t *testing.T) {
+		testCertPEM, _ := generateTestCert(t)
+		testChainPEM, _ := generateTestCert(t)
+		pemBundle := testCertPEM + testChainPEM
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/order/certificate/99001":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"id":99001,"status":"issued","certificate":{"id":88001,"common_name":"app.example.com"}}`))
+			case r.URL.Path == "/certificate/88001/download/format/pem_all":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(pemBundle))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		status, err := connector.GetOrderStatus(ctx, "99001")
+		if err != nil {
+			t.Fatalf("GetOrderStatus failed: %v", err)
+		}
+
+		if status.Status != "completed" {
+			t.Errorf("Expected status 'completed', got '%s'", status.Status)
+		}
+		if status.CertPEM == nil || *status.CertPEM == "" {
+			t.Error("CertPEM should not be empty for issued order")
+		}
+		if status.Serial == nil || *status.Serial == "" {
+			t.Error("Serial should not be empty for issued order")
+		}
+	})
+
+	t.Run("GetOrderStatus_Pending", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/order/certificate/99002" {
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"id":99002,"status":"pending","certificate":{"id":0}}`))
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		status, err := connector.GetOrderStatus(ctx, "99002")
+		if err != nil {
+			t.Fatalf("GetOrderStatus failed: %v", err)
+		}
+
+		if status.Status != "pending" {
+			t.Errorf("Expected status 'pending', got '%s'", status.Status)
+		}
+		if status.CertPEM != nil {
+			t.Error("CertPEM should be nil for pending order")
+		}
+	})
+
+	t.Run("GetOrderStatus_Rejected", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/order/certificate/99003" {
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"id":99003,"status":"rejected","certificate":{"id":0}}`))
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		status, err := connector.GetOrderStatus(ctx, "99003")
+		if err != nil {
+			t.Fatalf("GetOrderStatus failed: %v", err)
+		}
+
+		if status.Status != "failed" {
+			t.Errorf("Expected status 'failed', got '%s'", status.Status)
+		}
+	})
+
+	t.Run("RenewCertificate_NewOrder", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case strings.HasPrefix(r.URL.Path, "/order/certificate/"):
+				w.WriteHeader(http.StatusCreated)
+				w.Write([]byte(`{"id":99010,"status":"pending"}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:      "dc-test-key",
+			OrgID:       "12345",
+			ProductType: "ssl_basic",
+			BaseURL:     srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "renew.example.com")
+		renewReq := issuer.RenewalRequest{
+			CommonName: "renew.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.RenewCertificate(ctx, renewReq)
+		if err != nil {
+			t.Fatalf("RenewCertificate failed: %v", err)
+		}
+
+		if result.OrderID == "" {
+			t.Error("OrderID should not be empty")
+		}
+	})
+
+	t.Run("RevokeCertificate_Success", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if strings.HasSuffix(r.URL.Path, "/revoke") && r.Method == http.MethodPut {
+				if r.Header.Get("X-DC-DEVKEY") == "" {
+					w.WriteHeader(http.StatusForbidden)
+					return
+				}
+				w.WriteHeader(http.StatusNoContent)
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		reason := "keyCompromise"
+		revokeReq := issuer.RevocationRequest{
+			Serial: "88001",
+			Reason: &reason,
+		}
+
+		err := connector.RevokeCertificate(ctx, revokeReq)
+		if err != nil {
+			t.Fatalf("RevokeCertificate failed: %v", err)
+		}
+	})
+
+	t.Run("RevokeCertificate_Error", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte(`{"errors":[{"code":"certificate_not_found"}]}`))
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		revokeReq := issuer.RevocationRequest{
+			Serial: "00000",
+		}
+
+		err := connector.RevokeCertificate(ctx, revokeReq)
+		if err == nil {
+			t.Fatal("Expected error for revocation of nonexistent cert")
+		}
+	})
+
+	t.Run("GetOrderStatus_DownloadError", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/order/certificate/99004":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"id":99004,"status":"issued","certificate":{"id":88004}}`))
+			case r.URL.Path == "/certificate/88004/download/format/pem_all":
+				w.WriteHeader(http.StatusInternalServerError)
+				w.Write([]byte(`{"errors":["internal server error"]}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: srv.URL,
+		}
+		connector := digicert.New(config, logger)
+
+		_, err := connector.GetOrderStatus(ctx, "99004")
+		if err == nil {
+			t.Fatal("Expected error when download fails")
+		}
+		if !strings.Contains(err.Error(), "download") {
+			t.Logf("Got error: %v", err)
+		}
+	})
+
+	t.Run("GetRenewalInfo_ReturnsNil", func(t *testing.T) {
+		config := &digicert.Config{
+			APIKey:  "dc-test-key",
+			OrgID:   "12345",
+			BaseURL: "https://api.digicert.com",
+		}
+		connector := digicert.New(config, logger)
+
+		result, err := connector.GetRenewalInfo(ctx, "-----BEGIN CERTIFICATE-----\ntest\n-----END CERTIFICATE-----")
+		if err != nil {
+			t.Fatalf("GetRenewalInfo should not return error, got: %v", err)
+		}
+		if result != nil {
+			t.Fatal("GetRenewalInfo should return nil for DigiCert")
+		}
+	})
+
+	t.Run("DefaultProductType", func(t *testing.T) {
+		config := &digicert.Config{
+			APIKey: "dc-test-key",
+			OrgID:  "12345",
+			// ProductType intentionally left empty
+		}
+		connector := digicert.New(config, logger)
+
+		// Verify the connector was created (the default is set in New())
+		if connector == nil {
+			t.Fatal("Connector should not be nil")
+		}
+
+		// Verify via a request that uses the product type
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Verify the path includes the default product type
+			if strings.Contains(r.URL.Path, "ssl_basic") {
+				w.WriteHeader(http.StatusCreated)
+				w.Write([]byte(`{"id":99099,"status":"pending"}`))
+				return
+			}
+			t.Errorf("Expected path to contain 'ssl_basic', got: %s", r.URL.Path)
+			w.WriteHeader(http.StatusBadRequest)
+		}))
+		defer srv.Close()
+
+		// Reconfigure with test server URL
+		config.BaseURL = srv.URL
+		connector = digicert.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "test.example.com")
+		req := issuer.IssuanceRequest{
+			CommonName: "test.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.IssueCertificate(ctx, req)
+		if err != nil {
+			t.Fatalf("IssueCertificate with default product type failed: %v", err)
+		}
+		if result.OrderID == "" {
+			t.Error("OrderID should not be empty")
+		}
+	})
+}
+
+// generateTestCert creates a self-signed test certificate and returns the PEM strings.
+func generateTestCert(t *testing.T) (certPEM string, keyPEM string) {
+	t.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatalf("Failed to generate key: %v", err)
+	}
+
+	serial, _ := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	template := &x509.Certificate{
+		SerialNumber: serial,
+		Subject: pkix.Name{
+			CommonName: fmt.Sprintf("Test Certificate %s", serial.String()[:8]),
+		},
+		DNSNames:              []string{"test.example.com"},
+		KeyUsage:              x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	certBytes, err := x509.CreateCertificate(rand.Reader, template, template, &key.PublicKey, key)
+	if err != nil {
+		t.Fatalf("Failed to create certificate: %v", err)
+	}
+
+	certPEM = string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certBytes}))
+	keyPEM = string(pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)}))
+
+	return certPEM, keyPEM
+}
+
+// generateTestCSR creates a test CSR for the given common name.
+func generateTestCSR(t *testing.T, commonName string) (*x509.CertificateRequest, string) {
+	t.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatalf("Failed to generate key: %v", err)
+	}
+
+	csrTemplate := x509.CertificateRequest{
+		Subject: pkix.Name{
+			CommonName: commonName,
+		},
+		DNSNames:           []string{commonName},
+		SignatureAlgorithm: x509.SHA256WithRSA,
+	}
+
+	csrBytes, err := x509.CreateCertificateRequest(rand.Reader, &csrTemplate, key)
+	if err != nil {
+		t.Fatalf("Failed to create CSR: %v", err)
+	}
+
+	csrPEM := string(pem.EncodeToMemory(&pem.Block{
+		Type:  "CERTIFICATE REQUEST",
+		Bytes: csrBytes,
+	}))
+
+	csr, err := x509.ParseCertificateRequest(csrBytes)
+	if err != nil {
+		t.Fatalf("Failed to parse CSR: %v", err)
+	}
+
+	return csr, csrPEM
+}
diff --git a/internal/connector/issuer/vault/vault.go b/internal/connector/issuer/vault/vault.go
new file mode 100644
index 0000000..c1cd992
--- /dev/null
+++ b/internal/connector/issuer/vault/vault.go
@@ -0,0 +1,372 @@
+// Package vault implements the issuer.Connector interface for HashiCorp Vault PKI
+// secrets engine.
+//
+// Vault PKI provides a full-featured private CA with certificate signing, revocation,
+// CRL, and OCSP capabilities. This connector uses the Vault HTTP API to sign CSRs
+// via the /v1/{mount}/sign/{role} endpoint, authenticated with a Vault token.
+//
+// Vault issues certificates synchronously (like step-ca), so GetOrderStatus always
+// returns "completed". CRL and OCSP are delegated to Vault's own endpoints.
+//
+// Authentication: Vault token via X-Vault-Token header.
+//
+// Vault API used:
+//
+//	GET  /v1/sys/health                      - Health check
+//	POST /v1/{mount}/sign/{role}             - Sign CSR
+//	POST /v1/{mount}/revoke                  - Revoke certificate
+//	GET  /v1/{mount}/ca/pem                  - Get CA certificate
+package vault
+
+import (
+	"bytes"
+	"context"
+	"crypto/x509"
+	"encoding/json"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/shankar0123/certctl/internal/connector/issuer"
+)
+
+// Config represents the Vault PKI issuer connector configuration.
+type Config struct {
+	// Addr is the Vault server address (e.g., "https://vault.example.com:8200").
+	// Required. Set via CERTCTL_VAULT_ADDR environment variable.
+	Addr string `json:"addr"`
+
+	// Token is the Vault token for authentication.
+	// Required. Set via CERTCTL_VAULT_TOKEN environment variable.
+	Token string `json:"token"`
+
+	// Mount is the PKI secrets engine mount path.
+	// Default: "pki". Set via CERTCTL_VAULT_MOUNT environment variable.
+	Mount string `json:"mount"`
+
+	// Role is the PKI role name used for signing certificates.
+	// Required. Set via CERTCTL_VAULT_ROLE environment variable.
+	Role string `json:"role"`
+
+	// TTL is the requested certificate TTL (e.g., "8760h" for 1 year).
+	// Default: "8760h". Set via CERTCTL_VAULT_TTL environment variable.
+	TTL string `json:"ttl"`
+}
+
+// Connector implements the issuer.Connector interface for Vault PKI.
+type Connector struct {
+	config     *Config
+	logger     *slog.Logger
+	httpClient *http.Client
+}
+
+// New creates a new Vault PKI connector with the given configuration and logger.
+func New(config *Config, logger *slog.Logger) *Connector {
+	if config != nil {
+		if config.Mount == "" {
+			config.Mount = "pki"
+		}
+		if config.TTL == "" {
+			config.TTL = "8760h"
+		}
+	}
+
+	return &Connector{
+		config: config,
+		logger: logger,
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+// vaultResponse is the standard Vault API response wrapper.
+type vaultResponse struct {
+	Data    json.RawMessage `json:"data"`
+	Errors  []string        `json:"errors,omitempty"`
+	Warnings []string       `json:"warnings,omitempty"`
+}
+
+// signData holds the data returned from the /sign endpoint.
+type signData struct {
+	Certificate  string   `json:"certificate"`
+	IssuingCA    string   `json:"issuing_ca"`
+	CAChain      []string `json:"ca_chain"`
+	SerialNumber string   `json:"serial_number"`
+	Expiration   int64    `json:"expiration"`
+}
+
+// ValidateConfig checks that the Vault configuration is valid and the server is reachable.
+func (c *Connector) ValidateConfig(ctx context.Context, rawConfig json.RawMessage) error {
+	var cfg Config
+	if err := json.Unmarshal(rawConfig, &cfg); err != nil {
+		return fmt.Errorf("invalid Vault config: %w", err)
+	}
+
+	if cfg.Addr == "" {
+		return fmt.Errorf("Vault addr is required")
+	}
+
+	if cfg.Token == "" {
+		return fmt.Errorf("Vault token is required")
+	}
+
+	if cfg.Role == "" {
+		return fmt.Errorf("Vault role is required")
+	}
+
+	if cfg.Mount == "" {
+		cfg.Mount = "pki"
+	}
+	if cfg.TTL == "" {
+		cfg.TTL = "8760h"
+	}
+
+	// Health check
+	healthURL := cfg.Addr + "/v1/sys/health"
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, healthURL, nil)
+	if err != nil {
+		return fmt.Errorf("failed to create health check request: %w", err)
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("Vault not reachable at %s: %w", cfg.Addr, err)
+	}
+	defer resp.Body.Close()
+
+	// Vault health returns 200 for initialized+unsealed, 429 for standby, 472 for DR secondary,
+	// 473 for perf standby, 501 for uninitialized, 503 for sealed
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusTooManyRequests {
+		return fmt.Errorf("Vault health check returned status %d", resp.StatusCode)
+	}
+
+	c.config = &cfg
+	c.logger.Info("Vault PKI configuration validated",
+		"addr", cfg.Addr,
+		"mount", cfg.Mount,
+		"role", cfg.Role)
+
+	return nil
+}
+
+// IssueCertificate submits a CSR to Vault PKI for signing.
+func (c *Connector) IssueCertificate(ctx context.Context, request issuer.IssuanceRequest) (*issuer.IssuanceResult, error) {
+	c.logger.Info("processing Vault PKI issuance request",
+		"common_name", request.CommonName,
+		"san_count", len(request.SANs))
+
+	// Build the sign request body
+	signBody := map[string]interface{}{
+		"csr":         request.CSRPEM,
+		"common_name": request.CommonName,
+		"ttl":         c.config.TTL,
+	}
+
+	if len(request.SANs) > 0 {
+		signBody["alt_names"] = strings.Join(request.SANs, ",")
+	}
+
+	body, err := json.Marshal(signBody)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal sign request: %w", err)
+	}
+
+	// POST /v1/{mount}/sign/{role}
+	signURL := fmt.Sprintf("%s/v1/%s/sign/%s", c.config.Addr, c.config.Mount, c.config.Role)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, signURL, bytes.NewReader(body))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create sign request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Vault-Token", c.config.Token)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("Vault sign request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read sign response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		var vaultResp vaultResponse
+		if jsonErr := json.Unmarshal(respBody, &vaultResp); jsonErr == nil && len(vaultResp.Errors) > 0 {
+			return nil, fmt.Errorf("Vault sign returned status %d: %s", resp.StatusCode, strings.Join(vaultResp.Errors, "; "))
+		}
+		return nil, fmt.Errorf("Vault sign returned status %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	// Parse the Vault response
+	var vaultResp vaultResponse
+	if err := json.Unmarshal(respBody, &vaultResp); err != nil {
+		return nil, fmt.Errorf("failed to parse Vault response: %w", err)
+	}
+
+	var data signData
+	if err := json.Unmarshal(vaultResp.Data, &data); err != nil {
+		return nil, fmt.Errorf("failed to parse Vault sign data: %w", err)
+	}
+
+	if data.Certificate == "" {
+		return nil, fmt.Errorf("no certificate in Vault sign response")
+	}
+
+	// Parse the leaf certificate to extract metadata
+	certPEM := data.Certificate
+	block, _ := pem.Decode([]byte(certPEM))
+	if block == nil {
+		return nil, fmt.Errorf("failed to decode certificate PEM from Vault")
+	}
+
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse certificate: %w", err)
+	}
+
+	// Build chain PEM from ca_chain or issuing_ca
+	var chainPEM string
+	if len(data.CAChain) > 0 {
+		chainPEM = strings.Join(data.CAChain, "\n")
+	} else if data.IssuingCA != "" {
+		chainPEM = data.IssuingCA
+	}
+
+	// Normalize serial: Vault uses colon-separated hex (e.g., "aa:bb:cc"), convert to plain string
+	serial := normalizeSerial(data.SerialNumber)
+
+	orderID := fmt.Sprintf("vault-%s", serial)
+
+	c.logger.Info("Vault PKI certificate issued",
+		"common_name", request.CommonName,
+		"serial", serial,
+		"not_after", cert.NotAfter)
+
+	return &issuer.IssuanceResult{
+		CertPEM:   certPEM,
+		ChainPEM:  chainPEM,
+		Serial:    serial,
+		NotBefore: cert.NotBefore,
+		NotAfter:  cert.NotAfter,
+		OrderID:   orderID,
+	}, nil
+}
+
+// RenewCertificate renews a certificate by creating a new signing request.
+// For Vault PKI, renewal is functionally identical to issuance (new cert signed from CSR).
+func (c *Connector) RenewCertificate(ctx context.Context, request issuer.RenewalRequest) (*issuer.IssuanceResult, error) {
+	c.logger.Info("processing Vault PKI renewal request",
+		"common_name", request.CommonName,
+		"san_count", len(request.SANs))
+
+	return c.IssueCertificate(ctx, issuer.IssuanceRequest{
+		CommonName: request.CommonName,
+		SANs:       request.SANs,
+		CSRPEM:     request.CSRPEM,
+		EKUs:       request.EKUs,
+	})
+}
+
+// RevokeCertificate revokes a certificate at Vault PKI.
+func (c *Connector) RevokeCertificate(ctx context.Context, request issuer.RevocationRequest) error {
+	c.logger.Info("processing Vault PKI revocation request", "serial", request.Serial)
+
+	revokeBody := map[string]interface{}{
+		"serial_number": request.Serial,
+	}
+
+	body, err := json.Marshal(revokeBody)
+	if err != nil {
+		return fmt.Errorf("failed to marshal revoke request: %w", err)
+	}
+
+	revokeURL := fmt.Sprintf("%s/v1/%s/revoke", c.config.Addr, c.config.Mount)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, revokeURL, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("failed to create revoke request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Vault-Token", c.config.Token)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("Vault revoke request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("Vault revoke returned status %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	c.logger.Info("Vault PKI certificate revoked", "serial", request.Serial)
+	return nil
+}
+
+// GetOrderStatus returns the status of a Vault PKI order.
+// Vault signs synchronously, so orders are always "completed" immediately.
+func (c *Connector) GetOrderStatus(ctx context.Context, orderID string) (*issuer.OrderStatus, error) {
+	return &issuer.OrderStatus{
+		OrderID:   orderID,
+		Status:    "completed",
+		UpdatedAt: time.Now(),
+	}, nil
+}
+
+// GenerateCRL is not supported because Vault serves CRL directly at /v1/{mount}/crl.
+func (c *Connector) GenerateCRL(ctx context.Context, revokedCerts []issuer.RevokedCertEntry) ([]byte, error) {
+	return nil, fmt.Errorf("Vault serves CRL directly at /v1/%s/crl; use Vault's endpoint", c.config.Mount)
+}
+
+// SignOCSPResponse is not supported because Vault serves OCSP directly at /v1/{mount}/ocsp.
+func (c *Connector) SignOCSPResponse(ctx context.Context, req issuer.OCSPSignRequest) ([]byte, error) {
+	return nil, fmt.Errorf("Vault serves OCSP directly at /v1/%s/ocsp; use Vault's endpoint", c.config.Mount)
+}
+
+// GetCACertPEM retrieves the CA certificate from Vault PKI.
+func (c *Connector) GetCACertPEM(ctx context.Context) (string, error) {
+	caURL := fmt.Sprintf("%s/v1/%s/ca/pem", c.config.Addr, c.config.Mount)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, caURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create CA cert request: %w", err)
+	}
+	req.Header.Set("X-Vault-Token", c.config.Token)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("Vault CA cert request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("Vault CA cert returned status %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("failed to read CA cert response: %w", err)
+	}
+
+	return string(body), nil
+}
+
+// GetRenewalInfo returns nil, nil as Vault does not support ACME Renewal Information (ARI).
+func (c *Connector) GetRenewalInfo(ctx context.Context, certPEM string) (*issuer.RenewalInfoResult, error) {
+	return nil, nil
+}
+
+// normalizeSerial converts Vault's colon-separated hex serial (e.g., "aa:bb:cc:dd")
+// to a plain string representation suitable for storage.
+func normalizeSerial(serial string) string {
+	return strings.ReplaceAll(serial, ":", "-")
+}
+
+// Ensure Connector implements the issuer.Connector interface.
+var _ issuer.Connector = (*Connector)(nil)
diff --git a/internal/connector/issuer/vault/vault_test.go b/internal/connector/issuer/vault/vault_test.go
new file mode 100644
index 0000000..0ebeafe
--- /dev/null
+++ b/internal/connector/issuer/vault/vault_test.go
@@ -0,0 +1,527 @@
+package vault_test
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/json"
+	"encoding/pem"
+	"fmt"
+	"log/slog"
+	"math/big"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/shankar0123/certctl/internal/connector/issuer"
+	"github.com/shankar0123/certctl/internal/connector/issuer/vault"
+)
+
+func TestVaultConnector(t *testing.T) {
+	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	ctx := context.Background()
+
+	t.Run("ValidateConfig_Success", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/v1/sys/health" {
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"initialized":true,"sealed":false,"standby":false}`))
+				return
+			}
+			http.NotFound(w, r)
+		}))
+		defer srv.Close()
+
+		config := vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token-12345",
+			Mount: "pki",
+			Role:  "web-certs",
+			TTL:   "8760h",
+		}
+
+		connector := vault.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err != nil {
+			t.Fatalf("ValidateConfig failed: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_MissingAddr", func(t *testing.T) {
+		config := vault.Config{
+			Token: "s.test-token",
+			Role:  "web-certs",
+		}
+
+		connector := vault.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for missing addr")
+		}
+		if !strings.Contains(err.Error(), "addr is required") {
+			t.Errorf("Expected addr required error, got: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_MissingToken", func(t *testing.T) {
+		config := vault.Config{
+			Addr: "https://vault.example.com:8200",
+			Role: "web-certs",
+		}
+
+		connector := vault.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for missing token")
+		}
+		if !strings.Contains(err.Error(), "token is required") {
+			t.Errorf("Expected token required error, got: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_MissingRole", func(t *testing.T) {
+		config := vault.Config{
+			Addr:  "https://vault.example.com:8200",
+			Token: "s.test-token",
+		}
+
+		connector := vault.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for missing role")
+		}
+		if !strings.Contains(err.Error(), "role is required") {
+			t.Errorf("Expected role required error, got: %v", err)
+		}
+	})
+
+	t.Run("ValidateConfig_UnreachableVault", func(t *testing.T) {
+		config := vault.Config{
+			Addr:  "http://localhost:19999",
+			Token: "s.test-token",
+			Role:  "web-certs",
+		}
+
+		connector := vault.New(nil, logger)
+		rawConfig, _ := json.Marshal(config)
+		err := connector.ValidateConfig(ctx, rawConfig)
+		if err == nil {
+			t.Fatal("Expected error for unreachable Vault")
+		}
+	})
+
+	t.Run("IssueCertificate_Success", func(t *testing.T) {
+		testCertPEM, _ := generateTestCert(t)
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"initialized":true,"sealed":false}`))
+			case strings.HasPrefix(r.URL.Path, "/v1/pki/sign/"):
+				// Verify auth header
+				if r.Header.Get("X-Vault-Token") != "s.test-token" {
+					w.WriteHeader(http.StatusForbidden)
+					w.Write([]byte(`{"errors":["permission denied"]}`))
+					return
+				}
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(http.StatusOK)
+				resp := fmt.Sprintf(`{
+					"data": {
+						"certificate": %q,
+						"issuing_ca": %q,
+						"ca_chain": [%q],
+						"serial_number": "aa:bb:cc:dd:ee:ff",
+						"expiration": 1893456000
+					}
+				}`, testCertPEM, testCertPEM, testCertPEM)
+				w.Write([]byte(resp))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+			TTL:   "8760h",
+		}
+		connector := vault.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "app.example.com")
+
+		req := issuer.IssuanceRequest{
+			CommonName: "app.example.com",
+			SANs:       []string{"app.example.com", "www.example.com"},
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.IssueCertificate(ctx, req)
+		if err != nil {
+			t.Fatalf("IssueCertificate failed: %v", err)
+		}
+
+		if result.CertPEM == "" {
+			t.Error("CertPEM is empty")
+		}
+		if result.Serial == "" {
+			t.Error("Serial is empty")
+		}
+		if result.OrderID == "" {
+			t.Error("OrderID is empty")
+		}
+		if !strings.HasPrefix(result.OrderID, "vault-") {
+			t.Errorf("Expected OrderID to start with 'vault-', got '%s'", result.OrderID)
+		}
+		// Verify serial normalization (colons replaced with dashes)
+		if strings.Contains(result.Serial, ":") {
+			t.Errorf("Serial should not contain colons, got '%s'", result.Serial)
+		}
+		t.Logf("Vault issued cert: serial=%s, orderID=%s", result.Serial, result.OrderID)
+	})
+
+	t.Run("IssueCertificate_ServerError", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+			case strings.HasPrefix(r.URL.Path, "/v1/pki/sign/"):
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte(`{"errors":["invalid CSR"]}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "test.example.com")
+		req := issuer.IssuanceRequest{
+			CommonName: "test.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		_, err := connector.IssueCertificate(ctx, req)
+		if err == nil {
+			t.Fatal("Expected error for server error response")
+		}
+		if !strings.Contains(err.Error(), "invalid CSR") {
+			t.Logf("Got error: %v", err)
+		}
+	})
+
+	t.Run("IssueCertificate_Forbidden", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+			case strings.HasPrefix(r.URL.Path, "/v1/pki/sign/"):
+				w.WriteHeader(http.StatusForbidden)
+				w.Write([]byte(`{"errors":["permission denied"]}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.bad-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "test.example.com")
+		req := issuer.IssuanceRequest{
+			CommonName: "test.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		_, err := connector.IssueCertificate(ctx, req)
+		if err == nil {
+			t.Fatal("Expected error for forbidden response")
+		}
+		if !strings.Contains(err.Error(), "permission denied") {
+			t.Logf("Got error: %v", err)
+		}
+	})
+
+	t.Run("RenewCertificate_Success", func(t *testing.T) {
+		testCertPEM, _ := generateTestCert(t)
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+			case strings.HasPrefix(r.URL.Path, "/v1/pki/sign/"):
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(http.StatusOK)
+				resp := fmt.Sprintf(`{
+					"data": {
+						"certificate": %q,
+						"issuing_ca": %q,
+						"serial_number": "11:22:33:44:55:66",
+						"expiration": 1893456000
+					}
+				}`, testCertPEM, testCertPEM)
+				w.Write([]byte(resp))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		_, csrPEM := generateTestCSR(t, "renew.example.com")
+		renewReq := issuer.RenewalRequest{
+			CommonName: "renew.example.com",
+			CSRPEM:     csrPEM,
+		}
+
+		result, err := connector.RenewCertificate(ctx, renewReq)
+		if err != nil {
+			t.Fatalf("RenewCertificate failed: %v", err)
+		}
+
+		if result.Serial == "" {
+			t.Error("Serial is empty")
+		}
+	})
+
+	t.Run("RevokeCertificate_Success", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+			case r.URL.Path == "/v1/pki/revoke":
+				// Verify token
+				if r.Header.Get("X-Vault-Token") == "" {
+					w.WriteHeader(http.StatusForbidden)
+					return
+				}
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"data":{"revocation_time":1234567890}}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		reason := "keyCompromise"
+		revokeReq := issuer.RevocationRequest{
+			Serial: "aa-bb-cc-dd-ee-ff",
+			Reason: &reason,
+		}
+
+		err := connector.RevokeCertificate(ctx, revokeReq)
+		if err != nil {
+			t.Fatalf("RevokeCertificate failed: %v", err)
+		}
+	})
+
+	t.Run("RevokeCertificate_ServerError", func(t *testing.T) {
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/sys/health":
+				w.WriteHeader(http.StatusOK)
+			case r.URL.Path == "/v1/pki/revoke":
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte(`{"errors":["serial not found"]}`))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		revokeReq := issuer.RevocationRequest{
+			Serial: "00-00-00-00",
+		}
+
+		err := connector.RevokeCertificate(ctx, revokeReq)
+		if err == nil {
+			t.Fatal("Expected error for server error response")
+		}
+	})
+
+	t.Run("GetCACertPEM_Success", func(t *testing.T) {
+		expectedPEM := "-----BEGIN CERTIFICATE-----\nTESTCA\n-----END CERTIFICATE-----\n"
+
+		srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/v1/pki/ca/pem":
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(expectedPEM))
+			default:
+				http.NotFound(w, r)
+			}
+		}))
+		defer srv.Close()
+
+		config := &vault.Config{
+			Addr:  srv.URL,
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		caPEM, err := connector.GetCACertPEM(ctx)
+		if err != nil {
+			t.Fatalf("GetCACertPEM failed: %v", err)
+		}
+
+		if caPEM != expectedPEM {
+			t.Errorf("Expected CA PEM %q, got %q", expectedPEM, caPEM)
+		}
+	})
+
+	t.Run("GetOrderStatus_Synchronous", func(t *testing.T) {
+		config := &vault.Config{
+			Addr:  "https://vault.example.com:8200",
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		status, err := connector.GetOrderStatus(ctx, "vault-aa-bb-cc")
+		if err != nil {
+			t.Fatalf("GetOrderStatus failed: %v", err)
+		}
+
+		if status.Status != "completed" {
+			t.Errorf("Expected status 'completed', got '%s'", status.Status)
+		}
+		if status.OrderID != "vault-aa-bb-cc" {
+			t.Errorf("Expected OrderID 'vault-aa-bb-cc', got '%s'", status.OrderID)
+		}
+	})
+
+	t.Run("GetRenewalInfo_ReturnsNil", func(t *testing.T) {
+		config := &vault.Config{
+			Addr:  "https://vault.example.com:8200",
+			Token: "s.test-token",
+			Mount: "pki",
+			Role:  "web-certs",
+		}
+		connector := vault.New(config, logger)
+
+		result, err := connector.GetRenewalInfo(ctx, "-----BEGIN CERTIFICATE-----\ntest\n-----END CERTIFICATE-----")
+		if err != nil {
+			t.Fatalf("GetRenewalInfo should not return error, got: %v", err)
+		}
+		if result != nil {
+			t.Fatal("GetRenewalInfo should return nil for Vault")
+		}
+	})
+}
+
+// generateTestCert creates a self-signed test certificate and returns the PEM strings.
+func generateTestCert(t *testing.T) (certPEM string, keyPEM string) {
+	t.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatalf("Failed to generate key: %v", err)
+	}
+
+	serial, _ := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	template := &x509.Certificate{
+		SerialNumber: serial,
+		Subject: pkix.Name{
+			CommonName: "Test Certificate",
+		},
+		DNSNames:              []string{"test.example.com"},
+		KeyUsage:              x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	certBytes, err := x509.CreateCertificate(rand.Reader, template, template, &key.PublicKey, key)
+	if err != nil {
+		t.Fatalf("Failed to create certificate: %v", err)
+	}
+
+	certPEM = string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certBytes}))
+	keyPEM = string(pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)}))
+
+	return certPEM, keyPEM
+}
+
+// generateTestCSR creates a test CSR for the given common name.
+func generateTestCSR(t *testing.T, commonName string) (*x509.CertificateRequest, string) {
+	t.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatalf("Failed to generate key: %v", err)
+	}
+
+	csrTemplate := x509.CertificateRequest{
+		Subject: pkix.Name{
+			CommonName: commonName,
+		},
+		DNSNames:           []string{commonName},
+		SignatureAlgorithm: x509.SHA256WithRSA,
+	}
+
+	csrBytes, err := x509.CreateCertificateRequest(rand.Reader, &csrTemplate, key)
+	if err != nil {
+		t.Fatalf("Failed to create CSR: %v", err)
+	}
+
+	csrPEM := string(pem.EncodeToMemory(&pem.Block{
+		Type:  "CERTIFICATE REQUEST",
+		Bytes: csrBytes,
+	}))
+
+	csr, err := x509.ParseCertificateRequest(csrBytes)
+	if err != nil {
+		t.Fatalf("Failed to parse CSR: %v", err)
+	}
+
+	return csr, csrPEM
+}
diff --git a/internal/domain/connector.go b/internal/domain/connector.go
index 16c5b72..84a2659 100644
--- a/internal/domain/connector.go
+++ b/internal/domain/connector.go
@@ -69,6 +69,8 @@ const (
 	IssuerTypeGenericCA IssuerType = "GenericCA"
 	IssuerTypeStepCA    IssuerType = "StepCA"
 	IssuerTypeOpenSSL   IssuerType = "OpenSSL"
+	IssuerTypeVault     IssuerType = "VaultPKI"
+	IssuerTypeDigiCert  IssuerType = "DigiCert"
 )
 
 // TargetType represents the type of deployment target.
diff --git a/migrations/seed_demo.sql b/migrations/seed_demo.sql
index 7db4659..79e9b04 100644
--- a/migrations/seed_demo.sql
+++ b/migrations/seed_demo.sql
@@ -43,7 +43,9 @@ INSERT INTO issuers (id, name, type, config, enabled, created_at, updated_at) VA
   ('iss-acme-le',  'Let''s Encrypt Staging', 'acme',        '{"directory_url": "https://acme-staging-v02.api.letsencrypt.org/directory", "email": "admin@example.com", "challenge_type": "http-01"}', true,  NOW() - INTERVAL '150 days', NOW() - INTERVAL '150 days'),
   ('iss-stepca',   'step-ca Internal',       'stepca',      '{"ca_url": "https://ca.internal:9000", "provisioner_name": "certctl", "validity_days": 90}', true, NOW() - INTERVAL '120 days', NOW() - INTERVAL '120 days'),
   ('iss-acme-zs',  'ZeroSSL (EAB)',          'acme',        '{"directory_url": "https://acme.zerossl.com/v2/DV90", "email": "admin@example.com", "challenge_type": "http-01"}', true,  NOW() - INTERVAL '60 days', NOW() - INTERVAL '60 days'),
-  ('iss-openssl',  'Custom OpenSSL CA',      'openssl',     '{"sign_script": "/opt/ca/sign.sh", "timeout_seconds": 30}', false, NOW() - INTERVAL '30 days', NOW() - INTERVAL '30 days')
+  ('iss-openssl',  'Custom OpenSSL CA',      'openssl',     '{"sign_script": "/opt/ca/sign.sh", "timeout_seconds": 30}', false, NOW() - INTERVAL '30 days', NOW() - INTERVAL '30 days'),
+  ('iss-vault',    'HashiCorp Vault PKI',   'VaultPKI',    '{"addr": "https://vault.internal:8200", "mount": "pki", "role": "web-certs", "ttl": "8760h"}', true, NOW() - INTERVAL '20 days', NOW() - INTERVAL '20 days'),
+  ('iss-digicert', 'DigiCert CertCentral',  'DigiCert',    '{"base_url": "https://www.digicert.com/services/v2", "product_type": "ssl_basic"}', true, NOW() - INTERVAL '15 days', NOW() - INTERVAL '15 days')
 ON CONFLICT (id) DO NOTHING;
 
 -- ============================================================