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invowerk MCP Server

answering

invowerk is answering right now. Last checked moments ago. It exposes 6 tools. Last commit 15 Oct 2026.

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

Uptime history 15 days of history · worst day 98%
15 days agonow
100.0%
Uptime 24h
92 of 92 checks
6
Tools
read from the server
192 ms
Response time
average over 24h
0
Stars
last commit 15 Oct 2026

What changed 4

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 4 October 2026. No other catalogue keeps this.

15 Oct a tool description was rewritten generate_invoice
4 Oct 3 tools changed the parameters they ask for explain_errors, render_invoice, validate_invoice

invowerk missed one check this week

Everything else answered, so this is steady rather than shaky. We check every 15 minutes, which is how a one-off gets told apart from the start of a pattern, and how you hear about the next one within the hour instead of from your users.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 0 min ago.

run in your terminal
claude mcp add xrechnung-e-invoice-validator --transport http https://api.invowerk.dev/mcp/
~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "xrechnung-e-invoice-validator": {
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}
~/.codex/config.toml
[mcp_servers.xrechnung-e-invoice-validator]
url = "https://api.invowerk.dev/mcp/"
.cursor/mcp.json
{
  "mcpServers": {
    "xrechnung-e-invoice-validator": {
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}
.vscode/mcp.json
{
  "mcpServers": {
    "xrechnung-e-invoice-validator": {
      "url": "https://api.invowerk.dev/mcp/"
    }
  }
}

Available tools 6

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

convert
convert_invoice
Convert an e-invoice to UBL or CII. The result is checked before it is returned. Input: `invoice_base64` is the base64 of an XML invoice or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. `target_syntax` is "ubl" or "cii". `target_flavor` is optional, "en16931" or "xrechnung"; without it the flavor of the source is kept. Returns `xml`, `syntax`, `flavor` and `self_validation` (`valid`, `finding_count`). invowerk checks the converted XML before answering and never returns an invalid document. Input that cannot be read or converted fails with an error message. Credits: 3 per call.
explain
explain_errors
Explain rule codes in plain language. Works without an API key. Covers the codes of `validate_invoice` findings and hints: EN 16931, XRechnung, ZUGFeRD and invowerk's own hint codes (IW-*). Input: `codes` is a list of one or more codes, e.g. ["BR-CO-18", "BR-DE-21"]. Duplicates are removed. `lang` is "de" (default) or "en". Returns `lang` and `explanations`. Each explanation has `title`, `meaning`, `causes`, `fixes`, `severity`, `standard`, `bt_refs`, `xpath_hints` and `explain_url` (the German page for the code). If any code is unknown, the call fails and names the unknown codes. Credits: free. This tool is not metered.
generate
generate_invoice
Create a valid EN 16931 e-invoice (UBL or CII XML) from JSON. Input: `invoice` is a JSON object keyed on EN 16931 Business Terms, the same schema as `POST /v1/generate`, at most 4 MB. Main fields: `syntax` ("ubl" default, or "cii"), `flavor` ("en16931" default, or "xrechnung", which requires `buyer_reference`, the Leitweg-ID BT-10, and `payment_iban`), `invoice_number`, `issue_date` (YYYY-MM-DD), `currency`, `seller`, `buyer`, `lines`, `tax_breakdown`, `totals`. invowerk writes your amounts as given. It does not compute or correct them. Returns `xml`, `syntax`, `flavor` and `self_validation`. invowerk checks the XML before answering and never returns an invalid document. Invalid input, or XML that fails the check, returns an error, as does a busy (`engine_busy`) or overrunning (`engine_timeout`) generate. Credits: 5 per call.
parse
parse_invoice
Read an existing e-invoice into JSON keyed on EN 16931 Business Terms. The JSON is the input format of `generate_invoice`, so you can edit it and create the invoice again. Input: `invoice_base64` is the base64 of an XML invoice (UBL or CII) or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. A PDF may have at most 500 pages and 16 attachments. Returns `model` (the invoice as JSON), `detection` (`syntax`, `flavor`, `customization_id`) and `source` ("xml" or "pdf-embedded"). A file that cannot be read fails with an error that starts with an error code, e.g. a PDF without embedded XML, a UBL credit note, malformed XML, or a busy (`engine_busy`) or overrunning (`engine_timeout`) read. Credits: 2 per call.
render
render_invoice
Render an XML e-invoice (UBL or CII, e.g. XRechnung) as a readable HTML page. invowerk uses the KoSIT XRechnung visualization. Use it to show a person what an e-invoice contains. Input: `invoice_base64` is the base64 of the XML, at most 4 MB decoded, or pass the file as a download link in `file`. PDFs are not accepted. `lang` sets the label language, "de" (default) or "en". Returns `html` (a complete HTML document), `lang`, `flavor` (e.g. "xrechnung") and `syntax` (e.g. "ubl_invoice"). A file that is not an XML invoice, malformed XML or XML with a DOCTYPE fails with an error message, and so does a busy (`engine_busy`) or overrunning (`engine_timeout`) render. Credits: 1 per call.
validate
validate_invoice
Check an e-invoice against EN 16931 and German rules. Input: `invoice_base64` is the base64 of an XML invoice (UBL or CII) or a ZUGFeRD / Factur-X PDF, at most 4 MB decoded; or pass the file as a download link in `file`. `explain=true` adds an explanation to findings whose rule has one, in `lang` ("de" or "en"). `valid` is the result. For XRechnung the KoSIT validator decides. If it is unreachable, invowerk's own check with the same rules decides, `verdict_source` is "local" and `official_degraded` is true. `disagreement` is true when both ran and differ. `findings` lists each problem with `rule_id`, `severity` and `message`; pass the codes to `explain_errors` (free). `pdfa_verdict` is the PDF/A check of a PDF. `hints` never change `valid`. Unreadable input returns a finding, not an error. It fails with an error when the check is busy (`engine_busy`), ran longer than 20 s (`engine_timeout`) or the XML has more than 100,000 elements (`document_too_complex`). Credits: 1 per call.

Endpoints

URLTransportStateLatencyChecked
https://api.invowerk.dev/mcp/ streamable-http answering 187 ms 0 min ago

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invowerk — questions

Answers built from our own checks of this server.

What can invowerk do?
It exposes 6 tools, read directly from the server on our last check. Among them: convert_invoice, explain_errors, generate_invoice, parse_invoice, render_invoice, validate_invoice. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →
Is invowerk working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 192 ms. The bar chart above shows every period we have measured.
How do I connect invowerk?
Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does invowerk need an API key?
No. invowerk completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 6 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is invowerk?
It answers our handshake in 192 ms on average, which is faster than 64% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.
Is invowerk open source?
Yes — it is published under the MIT licence and 0 stars on GitHub. The source link is on this page, so you can read exactly what it does with your data before you connect it.