invowerk

dev.invowerk/xrechnung-e-invoice-validatorVersion 1.0.1

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

Status

Responds128 msNov 14, 2026, 14:26 UTCAnswered our handshake without sign-in.

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Last checked: Nov 14, 2026, 14:26 UTC
Latency: 128 ms
Remotes responding: 1 of 1
Sign-in: No sign-in
Hosting: EU hosting detected (detected, not a legal statement)
Registry data as of: Nov 14, 2026, 22:14 UTC

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Connect

Streamable HTTP

https://api.invowerk.dev/mcp/Responds128 msNov 14, 2026, 14:26 UTC

No sign-in

Claude Code

claude mcp add --transport http xrechnung-e-invoice-validator https://api.invowerk.dev/mcp/

Claude Desktop and claude.ai

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Settings > Connectors > Add custom connector
Name: xrechnung-e-invoice-validator
Remote MCP server URL: https://api.invowerk.dev/mcp/

Cursor

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

VS Code

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

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Tools

6 tools

Tools of invowerk
	Description		Read-only	Idempotent	Open world
`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.	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.	Not declared	Yes	Not declared	Yes
`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.	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.	Not declared	Yes	Not declared	No
`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. Input that breaks an EN 16931 or XRechnung rule returns an error naming each rule, e.g. BT-112 = BT-109 + BT-110 (BR-CO-15). Dates are YYYY-MM-DD, amounts go up to 999,999,999.99. 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.	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. Input that breaks an EN 16931 or XRechnung rule returns an error naming each rule, e.g. BT-112 = BT-109 + BT-110 (BR-CO-15). Dates are YYYY-MM-DD, amounts go up to 999,999,999.99. 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.	Not declared	Yes	Not declared	No
`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.	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.	Not declared	Yes	Not declared	Yes
`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.	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.	Not declared	Yes	Not declared	Yes
`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.	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.	Not declared	Yes	Not declared	Yes

Details

Registry status: Active
Published: Oct 4, 2026
Updated: Oct 4, 2026
Website: https://invowerk.dev/en/⁠ (opens in a new tab)
Repository: https://github.com/invowerk-dev/invowerk⁠ (opens in a new tab)
Categories (suggested): Invoicing and accountingSuggested categories are assigned automatically from the registry text and may be wrong. Verified operators can correct them.
GDPR: Not declared

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