wefact-mcp

An MCP server for the Dutch invoicing platform WeFact. Lets any MCP-compatible client (Claude Desktop, Claude Code, Cursor, Zed, …) read and modify your WeFact administration via natural language.

Stop typing in WeFact. Just tell Claude what to do.

Looking for the polished install + EULA + email support? Buy a commercial license: https://easeo.nl/diensten/wefact-mcp.

Quick start

1. Install

pip install wefact-mcp

2. Get a WeFact API key

In WeFact: Instellingen → API. Generate a key and whitelist your machine's IPv4 address (the API does not yet support IPv6).

3. Configure your MCP client

Claude Code

claude mcp add wefact -e WEFACT_API_KEY=your-key-here -- wefact-mcp

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "wefact": {
      "command": "wefact-mcp",
      "env": { "WEFACT_API_KEY": "your-key-here" }
    }
  }
}

Restart your MCP client and the WeFact tools should appear. Try:

Use the wefact-mcp whoami tool.

Tools

Generic escape hatch

Debtors (klanten)

list_debtors, get_debtor, create_debtor, update_debtor

Invoices (verkoopfacturen)

list_invoices, get_invoice, create_invoice, send_invoice, credit_invoice, mark_invoice_paid

Products

list_products, get_product

Subscriptions (abonnementen)

list_subscriptions, get_subscription

Credit invoices (inkoopfacturen)

list_credit_invoices, get_credit_invoice

Prompts

Field names

Tools that take fields or params use the WeFact field names verbatim (DebtorCode, InvoiceLines, PriceExcl, …). The docs at developer.wefact.com stay directly applicable — copy parameter names from the docs without translation.

Pagination & filtering

List tools fetch all pages by default. Pass limit_pages=1 for the first page only (useful while exploring). Pass modified_since="2026-01-01" for incremental sync.

Limitations

• WeFact's API is IPv4 only. Hosting this MCP behind an IPv6-only proxy will fail.
• WeFact rate-limits the API. The client retries on transient failures with exponential backoff; persistent 429s surface as errors.
• The API is not RESTful: every call is a POST to a single endpoint.
• Some list endpoints return a flat list rather than the controller-plural key; the client falls back to the first list-valued field. If you hit an oddity, fall back to wefact_request and parse the response yourself.

Security model

• The MCP server runs on your machine. No data passes through external servers.
• The WeFact API key stays in your local environment (or your MCP client's config) — never in our hands.
• No telemetry, no usage tracking, no phone-home.
• Source available for audit (see Repository).
• Independently reviewed for SQL injection, auth bypass, and credential leak vectors.

License

wefact-mcp is dual-licensed:

• AGPL-3.0-or-later — free for AGPL-compatible use. If you run a modified version on a server that interacts with users over a network, you must offer those users the source code (per AGPL §13).
• Commercial license — €197/year or €497 lifetime, ex VAT. For proprietary integrations, closed-source products, or hosted services that don't meet AGPL §13. Includes email support and 12 months of updates. Buy at https://easeo.nl/diensten/wefact-mcp.

For agency, white-label or platform partnerships — including a WeFact-side official integration — email nick@easeo.nl.

Disclaimer

This project is not affiliated with or endorsed by WeFact B.V. "WeFact" is a trademark of WeFact B.V. Use of this MCP server requires a valid WeFact account and API key, and is bound by WeFact's terms of service.