marselsel/Lexware-MCP-Server

git clone https://github.com/marselsel/Lexware-MCP-Server && cd Lexware-MCP-Server
cp .env.example .env && docker compose up --build
npm install && npm run build && LEXWARE_API_KEY=... MCP_AUTH_TOKEN=... npm start

Usage

• •Bring your own Lexware API key; the server is single-tenant per deployment and never stores anyone else's credentials.
• •Auth: OAuth 2.1 (required for web MCP / custom connectors in the Claude app, claude.ai, ChatGPT) or a static bearer token (Claude Code/Claude Desktop only).
• •Feature tiers via env: Read (always on), Drafts (LEXWARE_ENABLE_DRAFTS, default on), Finalize (LEXWARE_ENABLE_FINALIZE, default off); LEXWARE_READ_ONLY=true hard-forces read-only.
• •File receipts without base64 through the model: create-upload-ticket, then drag-and-drop or curl, then get-upload-result.

Key features

• ✓62 tools across the three tiers covering profile, contacts/articles, voucherlist, full documents, PDF rendering, file download, payments, and deeplinks.
• ✓Server-side upload-ticket flow keeps file bytes out of the model transcript (24-byte single-use tickets, 15-min validity).
• ✓upload-file-from-url with triple SSRF protection: host allow-list, resolved-address checks, and connection pinning (https only, 20 MB / 30 s cap).
• ✓OAuth 2.1 with dynamic client registration, audience verification, and optional domain allow-list.
• ✓Rate-limited (~2 req/s, token bucket), retry-aware Lexware client that never retries non-idempotent POSTs.

Best for

German-accounting-focused teams and solo bookkeepers who want an AI agent to read, draft, and file Lexware Office documents and receipts from chat.

Caveats

• ⚠It brokers real accounting data — finalized invoices are legally binding and you are responsible for their tax/legal correctness; MIT, no warranty.
• ⚠Static bearer auth does not work with web custom-connector UIs — OAuth is required for the Claude app, claude.ai web, and ChatGPT.
• ⚠Run a single instance: the rate limiter is per-process and upload tickets live in process memory (a restart voids open tickets).
• ⚠The server refuses to start without either OAUTH_ISSUER or MCP_AUTH_TOKEN unless MCP_ALLOW_UNAUTHENTICATED=true (trusted local use only).
• ⚠Serve over HTTPS; expose GET /status as the health check.