invowerk

dev.invowerkv1.0.0Updated Oct 1, 2026

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

VerifiedStreamable HTTPWeb executableBusiness & CommerceFinance

Overview

AI-generated overview

Validates European e-invoices such as ZUGFeRD, Factur-X, XRechnung and Peppol BIS and returns a rule report.

What it does
The server checks e-invoice files against ZUGFeRD 2.5.2 and Factur-X 1.09.2, XRechnung 3.0.2 (UBL and CII) and Peppol BIS Billing 3.0.21, with XRechnung routed through the KoSIT validator. PDFs are additionally checked for PDF/A conformance and against their embedded invoice data. Each check returns a report containing the file's SHA-256, the time, the rule sets applied and the result, and common rule messages include a cause and a suggested fix in German.
When to use it
Use it when an assistant needs to verify whether an invoice file is a valid, conformant e-invoice before sending or archiving it, or to explain validation errors in a document. It suits accounting, billing and public-sector invoicing workflows that handle German or European e-invoice formats.
Requirements
A remote streamable-HTTP endpoint; no local runtime or package is needed. An X-API-Key header is optional, since the anonymous tier works without a key but at a lower rate limit. The free tier includes 500 credits per month.
Before you install
The optional X-API-Key header is a secret and should be supplied through the client's configuration rather than pasted into shared files. Invoice files are uploaded to a third-party service for validation, so check the provider's privacy policy before sending sensitive billing data; the provider states invoices are processed in memory and not stored.

Installation

In SourceWeft

  1. Open invowerk in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "xrechnung-e-invoice-validator": {
      "type": "http",
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}

README

invowerk

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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.

Links

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:

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

Claude Code: /plugin marketplace add invowerk-dev/invowerk then /plugin install invowerk@invowerk (set INVOWERK_API_KEY for your key).

Cursor / Windsurf / Cline / Claude Desktop:

json
{  "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.

Source: README.md at commit 1b3b6df

Tools

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Version history

1
  1. v1.0.0LatestOct 1, 2026