diff --git a/.planning/ROADMAP.md b/.planning/ROADMAP.md
index 13c027c..3416c65 100644
--- a/.planning/ROADMAP.md
+++ b/.planning/ROADMAP.md
@@ -21,6 +21,7 @@ Decimal phases appear between their surrounding integers in numeric order.
 - [ ] **Phase 6: Desktop Client & CI/CD** - Tauri wrapper for Windows/Linux and automated Gitea integration
 - [x] **Phase 7: DKV Fleet Module** - Automated DKV invoice processing via email monitoring, PDF parsing, and Excel export with driver mapping (completed 2026-06-27)
 - [x] **Phase 8: Dashboard Widgets Vollimplementierung** - Calculator, Favorites, and Stopwatch widgets plus unified grid constraints across all dashboard widgets (completed 2026-07-01)
+- [ ] **Phase 9: Cert Manager Module** - Server-side certificate toolkit: upload/paste, inspect, split chains, merge/bundle, convert formats, password-protected PFX support
 
 ## Phase Details
 
@@ -278,10 +279,29 @@ Decimal phases appear between their surrounding integers in numeric order.
 
 **UI hint**: yes
 
+### Phase 9: Cert Manager Module
+
+**Goal:** Users can upload or paste certificates in any common format, inspect their details, split fullchain/P7B bundles into individual certificates, merge certs into chains or PFX bundles, and convert between formats — all processed server-side with no database persistence.
+**Mode:** mvp
+**Depends on**: Phase 3
+**Requirements**: CERT-01, CERT-02, CERT-03, CERT-04, CERT-05, CERT-06
+**Success Criteria** (what must be TRUE):
+
+  1. User can upload a cert file (PEM, DER, PFX/P12, CRT, CER, P7B) or paste PEM/CRT text and see parsed details (subject, issuer, validity, SANs, fingerprint)
+  2. User can split a fullchain.pem or P7B bundle into individual certificate files (downloadable)
+  3. User can merge multiple cert files into a PEM chain or a PFX bundle (with password)
+  4. User can convert between PEM, DER, PFX/P12, P7B, CRT/CER formats
+  5. Password-protected PFX/PKCS12 files can be opened (password prompt) and created (password input)
+  6. Module appears in the module registry with slug `cert-manager`
+
+**Plans**: 0/0 plans created
+
+**UI hint**: yes
+
 ## Progress
 
 **Execution Order:**
-Phases execute in numeric order: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8
+Phases execute in numeric order: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9
 
 | Phase | Plans Complete | Status | Completed |
 |-------|----------------|--------|-----------|
@@ -293,3 +313,4 @@ Phases execute in numeric order: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8
 | 6. Desktop Client & CI/CD | 2/3 | In Progress|  |
 | 7. DKV Fleet Module | 6/6 | Complete   | 2026-06-27 |
 | 8. Dashboard Widgets Vollimplementierung | 4/4 | Complete   | 2026-07-01 |
+| 9. Cert Manager Module | 0/0 | Not started | - |
diff --git a/.planning/phases/09-cert-manager-module/09-CONTEXT.md b/.planning/phases/09-cert-manager-module/09-CONTEXT.md
new file mode 100644
index 0000000..00b3b80
--- /dev/null
+++ b/.planning/phases/09-cert-manager-module/09-CONTEXT.md
@@ -0,0 +1,104 @@
+# Phase 9 Context: Cert Manager Module
+
+**Date:** 2026-07-01
+**Status:** Ready for planning
+
+---
+
+## <domain>
+Certificate management toolkit module. Users upload or paste certificates, inspect parsed details, split fullchain/bundle files into individual certs, merge certs into chains or PFX bundles, and convert between formats. All processing server-side, fully ephemeral (no database storage).
+</domain>
+
+---
+
+## <decisions>
+
+### Processing & Persistence
+- **Server-side API** — All crypto operations happen in the NestJS backend, not client-side JavaScript
+- **Ephemeral** — No Prisma schema changes, no DB tables, no file storage. Upload → process → return result/download
+- Files are held in memory during request only (multer `memoryStorage`)
+
+### Operations
+- **Inspect** — Parse any cert and return: subject, issuer, validity dates, SANs, key type/size, fingerprint (SHA-1 + SHA-256), serial, signature algorithm
+- **Split** — Accept fullchain.pem or P7B bundle; return array of individual certs (each downloadable as .crt/.pem)
+- **Merge** — Combine multiple certs into:
+  - PEM chain (concatenated)
+  - PFX/PKCS12 bundle (cert + optional private key, with password)
+- **Convert** — Between: PEM ↔ DER ↔ PFX/P12 ↔ P7B ↔ CRT/CER
+
+### Input Modes
+- **File upload** — All formats: `.pem`, `.crt`, `.cer`, `.der`, `.pfx`, `.p12`, `.p7b`, `.p7c`
+- **Text paste** — PEM/CRT content pasted directly into textarea (auto-detected via `-----BEGIN` header)
+- **Password field** — Shown conditionally when format is PFX/P12 (both for reading and creating)
+
+### Supported Formats
+| Format | Read | Write |
+|--------|------|-------|
+| PEM (.pem, .crt, .cer) | ✓ | ✓ |
+| DER (.der, .cer binary) | ✓ | ✓ |
+| PFX/PKCS12 (.pfx, .p12) | ✓ with password | ✓ with password |
+| P7B/PKCS7 (.p7b, .p7c) | ✓ | ✓ |
+
+### Library
+- **`node-forge`** — Battle-tested Node.js crypto library; handles PEM, DER, PFX/PKCS12, P7B/PKCS7 in one package. No native bindings needed (pure JS, Docker-friendly).
+
+### Module Registry
+- **Slug:** `cert-manager`
+- **Category:** `security-tools`
+- **Pattern:** Same as Domaincheck — `OnModuleInit` seed, `@UseModule('cert-manager')` guard
+
+### UI Layout
+- Tab-based: **Analysieren** | **Aufteilen** | **Zusammenführen** | **Konvertieren**
+- Shared file drop zone + text area at top, tabs below for operation selection
+- Password field appears conditionally (PFX/P12 detected or PFX output selected)
+- Results shown inline with download buttons per cert
+
+### API Endpoints
+All under `/modules/cert-manager`:
+- `POST /parse` — inspect single cert (multipart or JSON with PEM text)
+- `POST /split` — split fullchain/P7B → array of certs
+- `POST /merge` — merge certs → PEM chain or PFX
+- `POST /convert` — convert format
+
+### Frontend Path
+- `apps/web/src/app/(portal)/modules/cert-manager/page.tsx`
+- `apps/web/src/app/(portal)/modules/cert-manager/actions.ts`
+
+</decisions>
+
+---
+
+## <canonical_refs>
+- `.planning/ROADMAP.md` — Phase 9 definition, requirements CERT-01 through CERT-06
+- `apps/api/src/domaincheck/` — Module pattern to follow (controller, seed, guard usage)
+- `apps/web/src/app/(portal)/modules/domaincheck/` — Frontend module pattern
+- `apps/api/src/module-registry/` — Registry service + UseModule guard
+</canonical_refs>
+
+---
+
+## <code_context>
+
+### Reusable Patterns
+- **NestJS module registration:** `domaincheck.module.ts` → `OnModuleInit` + `seedModule()`
+- **Module guard:** `@UseModule('slug')` from `module-registry/module.guard`
+- **File upload:** Use `@nestjs/platform-express` multer with `memoryStorage` (no disk writes)
+- **Frontend actions:** `actions.ts` with `'use server'` calling `/api-proxy/modules/[slug]/[endpoint]`
+- **Frontend page:** Client component with `useTranslations`, Card layout (`rounded-lg border border-border bg-card`)
+
+### No Prisma Changes
+Phase adds zero new database tables. `node-forge` runs entirely in memory.
+
+### Dependencies to Add
+- API: `node-forge` + `@types/node-forge`
+- No new frontend deps (file input + fetch already available)
+</code_context>
+
+---
+
+## <deferred>
+- Certificate expiry monitoring / alerts (would need DB + cron — separate phase)
+- Certificate store / saved cert library (needs DB — separate phase)
+- OCSP / CRL revocation check (nice to have, out of scope here)
+- Private key generation (out of scope — cert manager, not CA)
+</deferred>