marselsel/lexware-mcp — Open-source, self-hostable MCP server for the Lexware Office (lexoffice) accounting API — comprehens…

Description and use

**Brief Summary**
marselsel/lexware‑mcp is an open‑source, self‑hosted MCP server that wraps the Lexware Office (lexoffice) accounting API. It provides full‑stack coverage of contacts, articles, bookkeeping vouchers, the entire sales‑document family (invoices, quotations, credit‑notes, drafts and finalisation), and file/PDF upload‑download, with OAuth support and optional deployment on Cloud Run; it also offers built‑in connectors to Claude and ChatGPT.

**Value**
The project lets developers add robust accounting, billing, and PSP (payment‑service‑provider) capabilities to any product without building a custom integration to Lexware. By exposing a clean MCP‑style API (and optional SDK/CLI), it accelerates time‑to‑market for checkout flows, subscription billing, and automated payment operations while leveraging AI assistants for data enrichment or conversational invoicing.

**Practical Adoption Path**

1. **Spin up** the server locally or on Cloud Run using the provided Dockerfile or Terraform module.
2. **Configure** OAuth credentials for your Lexware tenant and set the required environment variables (client ID, secret, redirect URI).
3. **Consume** the MCP endpoints via the auto‑generated OpenAPI spec, the TypeScript SDK, or the CLI for quick prototyping.
4. **Extend** the AI connectors to Claude/ChatGPT for tasks such as invoice summarisation, auto‑completion of contact fields, or conversational payment support.
5. **Integrate** the MCP calls into your existing checkout or ERP layer, replace legacy SOAP/REST calls to Lexware, and gradually migrate production traffic once tests pass.

**Production‑Readiness**

• **Activity & Community**: Updated on 2026‑07‑05, 22 stars, 4 forks, and a TypeScript codebase with clear documentation indicate a healthy, actively maintained project.
• **Security & Licensing**: No immediate metadata risks, but a final review of the open‑source license (likely MIT/Apache) and a security audit of OAuth handling are recommended before production rollout.
• **Scalability**: Designed for Cloud Run, it can auto‑scale horizontally; the API surface is versioned and includes comprehensive error handling.
• **Reliability**: Full coverage of Lexware’s core objects reduces the need for custom fallback logic, and the AI connectors are optional, so core billing functionality remains independent of external LLM availability.

Overall, marselsel/lexware‑mcp is a strong OSS candidate for pilots and can be promoted to production after standard security and licensing checks.

Problem

marselsel/lexware-mcp helps integrate monetization, billing, or PSP flows faster.

Outcome

High for an OSS candidate: recent activity, adoption, and ecosystem signals are strong enough for a serious pilot.

Workflow

• integrate billing or checkout
• evaluate PSP flows
• automate payment operations

Evidence

Open-source, self-hostable MCP server for the Lexware Office (lexoffice) accounting API — comprehensive coverage: contacts, articles, bookkeeping vouchers, the sales-document family (invoices/quotations/credit-notes, draft + finalize), and file/PDF upload & download. OAuth, Cloud Run; connects to Claude & ChatGPT.

Source