invowerk

MCP serverCommerce & finance

Lets your agent check e-invoices against European standards like ZUGFeRD, Factur-X, XRechnung and Peppol.

Available today. Use it from your connected AI after setup.

Needs your own API account. Keys stay in your vault.

Add ahel to your AI once: Claude, ChatGPT, Cursor, Claude Code or Codex. Then ask it to use this.

Then ask your AI: use invowerk to validate invoice

About this server

E-invoice checker for ZUGFeRD, Factur-X, XRechnung and Peppol BIS. Free web tool, API and MCP.

Install invowerk

The server’s own address, for the clients that take one directly. Or connect ahel onceand every client you use reads it from one address, with the account kept on ahel rather than in each client’s config.

Claude Code
claude mcp add --transport http --scope user invowerk 'https://api.invowerk.dev/mcp/'
Run it once in your project, then open /mcp to approve any sign-in the server asks for.
Claude Desktop
https://api.invowerk.dev/mcp/
Add a custom connector in Settings, paste this address, and approve the sign-in.
Cursor
cursor://anysphere.cursor-deeplink/mcp/install?name=invowerk&config=eyJ1cmwiOiJodHRwczovL2FwaS5pbnZvd2Vyay5kZXYvbWNwLyJ9
Open the link and Cursor adds the server at that address.
ChatGPT
https://api.invowerk.dev/mcp/
In Settings, enable Developer mode, create an MCP app, and paste this address. Your plan and workspace must allow custom apps.
Codex
codex mcp add invowerk --url 'https://api.invowerk.dev/mcp/'
Run it once, then sign in with codex mcp login invowerk if the server asks for an account.

From the project's README

As published by invowerk-dev/invowerk in README.md.

E-Rechnung prüfen: ZUGFeRD und XRechnung

invowerk checks e-invoices: ZUGFeRD 2.5.2 and Factur-X 1.09.2 PDFs, XRechnung 3.0.2 (UBL and CII) and Peppol BIS Billing 3.0.21. XRechnung goes through the KoSIT validator. PDFs are also checked for PDF/A and against their embedded invoice data. Common rule messages come with cause and fix in German. Each check returns a report with the file's SHA-256, time, rule sets and result. The Prüfstand test files and their expected results are public. Invoices are processed in memory, not stored. Free web tool; REST API and MCP server with 500 free credits per month.

MCP server

Streamable-HTTP endpoint: https://api.invowerk.dev/mcp/ — the anonymous tier works without a key; an API key raises the limits.

Claude Code:

claude mcp add --transport http invowerk https://api.invowerk.dev/mcp/

Cursor / Windsurf / Cline / Claude Desktop:

{
  "mcpServers": {
    "invowerk": {
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}

One-click installs for every client: https://invowerk.dev/connect

API

Base URL https://api.invowerk.dev/ — authenticate with an X-API-Key header; anonymous calls work at a lower rate limit.

Tools it offers (6)

What this server listed when ahel dialed its public endpoint in Sep 2026, with no key and no account of yours. The names are the server’s own.

validate_invoice
render_invoice
explain_errors
generate_invoice
parse_invoice
convert_invoice

Signals

Last commit: Sep 2026

Advanced

Delivery: invowerk MCP server → your ahel connector (mcp.ahel.ai) → your AI.
Item type: mcp-server
Key: dev-invowerk-invowerk
Source: github.com/invowerk-dev/invowerk
Hosted endpoint: https://api.invowerk.dev/mcp/

github.com/invowerk-dev/invowerk

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