invowerk

dev.invowerkv1.0.0Updated Sep 28, 2026

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

VerifiedStreamable HTTPWeb executableBusiness & Commerce

Overview

AI-generated overview

Checks ZUGFeRD, Factur-X, XRechnung and Peppol BIS e-invoices and returns a validation report with rule messages and file hash.

What it does
Validates e-invoices against ZUGFeRD 2.5.2, 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. PDF/A conformance and the invoice data embedded in the PDF are also checked. Each check returns a report with the file's SHA-256, timestamp, rule sets and result, and common rule messages include a cause and a fix in German.
When to use it
Useful when an assistant has to verify an incoming or outgoing e-invoice before submission or archiving, or has to explain why a validation run failed.
Requirements
A remote MCP endpoint over streamable HTTP; nothing is installed locally. The anonymous tier works without credentials, and an X-API-Key header is optional and raises the rate limits. Network access is required, and the invoice files are uploaded to the service for checking.
Before you install
Uploaded invoices leave the local machine and go to a third-party service; the README states they are processed in memory and not stored. Supplying X-API-Key sends a secret to the provider. Usage is metered in credits (500 free per month), so heavier use may require a paid plan.

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": {
    "invowerk": {
      "type": "http",
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}

README

invowerk

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/

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 b21b006

Tools

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Version history

1
  1. v1.0.0LatestSep 28, 2026