Conformo e-invoicing

io.github.arsalmuradPublished by GitHub account arsalmuradv0.2.3Updated Nov 6, 2026

Create and check EU e-invoices (XRechnung, ZUGFeRD, Factur-X, Peppol) locally. Free, no API key.

VerifiedSTDIODesktop onlyFinanceBusiness & Commerce

Overview

AI-generated overview

Locally run MCP server that lets an assistant create, validate, convert and parse European EN 16931 e-invoices such as XRechnung, Peppol BIS and…

What you can do
  • Build e-invoice XML in CII, UBL, XRechnung or Peppol BIS from structured invoice data, or produce a Factur-X/ZUGFeRD PDF/A-3 with the XML embedded
  • Validate an invoice against XSD, CEN EN 16931 Schematron and KoSIT or Peppol rules, and report which rule sets ran
  • Convert an existing invoice between syntaxes and profiles, and parse XML or PDF invoices back into a structured invoice object
  • Look up country e-invoicing mandates, dates, thresholds and required formats
  • Explain a validation rule id with official wording, meaning and how to fix it
When to use it
Useful when you need to issue or check EU e-invoices from a chat client without sending documents to a third-party service, for example drafting an XRechnung, checking a received invoice, or turning a UBL invoice into a ZUGFeRD PDF.
Requirements
Runs as a local stdio process via npx, so Node.js 20 or newer is needed. No account, API key or environment variable is required for normal use. Optional settings exist for HTTP mode and for lifting the PDF output path limit.
Before you install
create_invoice_pdf can write a PDF file to disk; by default the path must stay inside the working directory and must not exist unless overwrite is set. Invoices contain personal and commercial data, and the optional HTTP mode has no authentication or TLS, so it should sit behind a proxy. A valid result only means the listed rule sets passed, not that an authority or buyer will accept the invoice, and country data is not legal advice.

Installation

In SourceWeft

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

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

@conformo/mcp-server

Let Claude, Cursor or any MCP client make and check European e-invoices: XRechnung, ZUGFeRD / Factur-X PDF, Peppol BIS Billing 3.0, plain CII and UBL.

  • Runs on your machine. No account, no API key, no usage limits. Invoices never leave your computer; no tool makes a network call.
  • Same verdict as the official validator. validate_invoice runs the official KoSIT, CEN and Peppol rules plus the XSDs. Its verdicts match the official KoSIT validator 100% on the official test invoices, and the full comparison is public.
  • Explains what to fix. Every failed rule comes back with the publisher's message, and the common ones also with a plain-language explanation and fix.
  • Free and open source (Apache-2.0). Rule sets are pinned and a daily job tracks KoSIT, CEN and Peppol releases (how).

Quick start for Claude Code: claude mcp add conformo -- npx -y @conformo/mcp-server. Other clients are below. Needs Node.js 20 or newer. MCP Registry name: io.github.arsalmurad/conformo.

Then ask your agent things like:

  • "Make an XRechnung for Stadt Musterstadt, Leitweg-ID 04011000-1234512345-06, 10 hours of consulting at 95 EUR, and check it."
  • "Is this invoice valid? Explain every error and fix it." (paste the XML, or give a ZUGFeRD PDF)
  • "Turn this UBL invoice into a ZUGFeRD PDF."
  • "What does BR-DE-15 mean?"

Every tool is a thin wrapper over @conformo/toolkit. Two transports: stdio (default, for desktop clients) and stateless Streamable HTTP (for a shared deployment).

Tools

ToolWhat it doesRead-only
create_invoiceStructured invoice (JSON object) to XML: cii, cii-extended, ubl, xrechnung-cii, xrechnung-ubl, peppol-ubl.yes
create_invoice_pdfSame input to a Factur-X / ZUGFeRD PDF/A-3 (en16931, xrechnung, extended). Returns base64, or writes outputPath.no
validate_invoiceXML text or base64 PDF. Detects syntax and profile, runs XSD and the matching rule sets, reports which ran. Optional country FR or DE.yes
convert_invoiceXML or PDF in, another syntax out.yes
parse_invoiceXML or PDF to the invoice JSON model.yes
get_country_requirementsMandates, dates, thresholds and sources per country, plus what Conformo itself supports.yes
explain_validation_ruleA rule id such as BR-CO-15: official wording, plain-language meaning and fix.yes

All tools declare an outputSchema and return structuredContent plus a text fallback. Money is always integer minor units (EUR 12.34 is 1234). The input schema of create_invoice documents every field with its BT/BG identifier. Input problems come back as an isError result listing every issue (path, BT id, message), never a stack trace.

Install and configure

The commands below use the published package name. From a checkout, replace npx -y @conformo/mcp-server with npx tsx /absolute/path/to/conformo/packages/mcp-server/src/server.ts.

Claude Desktop

Add to claude_desktop_config.json (Settings, Developer, Edit Config):

json
{  "mcpServers": {    "conformo": {      "command": "npx",      "args": ["-y", "@conformo/mcp-server"]    }  }}

On Windows, if npx is not found, use "command": "cmd" with "args": ["/c", "npx", "-y", "@conformo/mcp-server"].

Claude Code

bash
claude mcp add conformo -- npx -y @conformo/mcp-server# or against a remote deploymentclaude mcp add --transport http conformo https://mcp.example.com/mcp

Cursor

.cursor/mcp.json in the project, or ~/.cursor/mcp.json for all projects:

json
{  "mcpServers": {    "conformo": {      "command": "npx",      "args": ["-y", "@conformo/mcp-server"]    }  }}

Working directory and outputPath

create_invoice_pdf can write a file instead of returning base64. The path must end in .pdf, stay inside the server's working directory, and not exist yet unless overwrite: true. Set CONFORMO_MCP_ALLOW_ANY_PATH=1 to lift the directory limit.

HTTP mode

bash
conformo-mcp --http --port 8787 --host 127.0.0.1 --max-body-bytes 8388608
FlagEnvDefault
--portCONFORMO_MCP_PORT8787 (0 picks a free port; the URL is printed on stderr)
--hostCONFORMO_MCP_HOST127.0.0.1
--max-body-bytesCONFORMO_MCP_MAX_BODY_BYTES8388608 (8 MiB); larger bodies get 413

Endpoints: POST /mcp (JSON-RPC, JSON responses), GET /healthz (liveness), GET/DELETE /mcp answer 405. The server is stateless: a fresh server and transport per request, no session ids, no data kept between calls. It has no authentication and no TLS.

Remote deployment

Do not expose the port directly. Run it on a private interface and put a reverse proxy with TLS and authentication in front (a bearer token check, mTLS, or your identity-aware proxy). Because it is stateless you can run any number of replicas behind a load balancer with no sticky sessions. Bind to 0.0.0.0 only inside a container or private network.

Dockerfile:

dockerfile
FROM node:22-slimWORKDIR /appRUN npm install -g @conformo/mcp-serverENV CONFORMO_MCP_HOST=0.0.0.0 CONFORMO_MCP_PORT=8787EXPOSE 8787USER nodeHEALTHCHECK CMD node -e "fetch('http://127.0.0.1:8787/healthz').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"CMD ["conformo-mcp", "--http"]

Caddy example (token auth and TLS in front):

mcp.example.com {  @authed header Authorization "Bearer {env.MCP_TOKEN}"  handle @authed {    reverse_proxy 127.0.0.1:8787  }  respond "unauthorized" 401}

Note that invoices contain personal and commercial data: whoever can reach the endpoint can send invoices through it, and you carry the usual obligations for the traffic your proxy logs.

What it does not do

  • It does not transmit invoices: no Peppol access point, no French PA/PDP, no KSeF, no SdI. It produces and checks documents only.
  • It does not support FatturaPA or Facturae (no serializer, reader or validator). KSeF FA(3) is limited to writing domestic PLN invoices and checking them against the Ministry of Finance XSD; it cannot read them.
  • A valid: true means the rule sets listed in ruleSets and the XSD passed. It is not a statement that any tax authority, buyer or network will accept the invoice.
  • It does not compute anything you did not supply beyond totals and the VAT breakdown; exchange rates (BT-111) and exemption reasons are your input.
  • get_country_requirements reports a sourced dataset; entries marked unverified are not confirmed from an official source. It is not legal advice.
  • No authentication, authorisation, rate limiting or persistence in the server itself.
  • Local PDF writing is limited to the working directory unless you opt out; there is no network access from any tool.

Design decisions are recorded in DECISIONS.txt.

Source: packages/mcp-server/README.md at commit bf8516b

Tools

7

create_invoice

Create an e-invoice (XML)

Builds e-invoice XML from structured invoice data: EN 16931 CII or UBL, XRechnung (CII or UBL) or Peppol BIS Billing 3.0, chosen by `format`. Use it for a new invoice that software will read. For a printable PDF with the XML inside, use create_invoice_pdf; to change the syntax of an invoice you already have, use convert_invoice. Pass `invoice` as a JSON object, not a string. Every money field ends in "Minor" and is an integer in minor units (EUR 12.34 = 1234); totals and the VAT breakdown are computed, so do not send them. If fields are missing or wrong it returns an error listing every problem (path, BT id, message) and produces nothing; fix them all and call again. It runs locally and does not send the invoice anywhere. It does not run the official rule sets: call validate_invoice on the XML before it goes out.

Parametersformatrequiredinvoicerequired

create_invoice_pdf

Create a Factur-X / ZUGFeRD PDF

Builds a Factur-X / ZUGFeRD invoice: a PDF/A-3b page a person can read, with the EN 16931 XML embedded for software. Use it when the invoice goes to a person or by e-mail. For XML only, such as an XRechnung uploaded to a German public-sector portal, use create_invoice. Takes the same `invoice` object as create_invoice, money in integer minor units. `language` changes only the printed labels; the embedded XML is identical in every language. By default the PDF comes back as base64, which can be large; pass `outputPath` to write the file instead. Writing stays inside the server's working directory and never replaces an existing file unless `overwrite` is true. The same input always gives the same bytes, and nothing is sent anywhere. Check the result with validate_invoice (pass pdfBase64).

ParametersinvoicerequiredprofilelanguagetemplateoverwriteoutputPath

validate_invoice

Validate an e-invoice

Checks an e-invoice against the official rule sets on this machine: the XSD, the EN 16931 Schematron from CEN, and the KoSIT XRechnung or Peppol BIS rules when the document declares them. Use it before sending an invoice you created and when you receive one. To read the invoice's data use parse_invoice; to explain one failed rule in depth use explain_validation_rule. Accepts XML or a Factur-X / ZUGFeRD PDF, whose embedded XML is checked; syntax and profile are detected from the document. A `valid` result means the listed `ruleSets` passed, not that a tax authority or buyer will accept the invoice, so report which rule sets ran and never claim more. Each failure carries the publisher's message and, for common rules, a plain-language fix. Input that is not an invoice comes back as an error result, not as invalid. The check runs offline; nothing is uploaded.

ParametersxmlxsdcountryprofilepdfBase64

convert_invoice

Convert an e-invoice between syntaxes

Rewrites an existing e-invoice in another syntax, for example CII to UBL, or plain EN 16931 to XRechnung or Peppol BIS. Use it when you already hold an invoice document. To build one from data use create_invoice; to get a PDF from XML use parse_invoice, then create_invoice_pdf. Accepts XML or a Factur-X / ZUGFeRD PDF. Nothing is invented: a target such as XRechnung may need data the source lacks, so read `warnings` and run validate_invoice on the result. A document it cannot read comes back as an error result with the reason. Runs locally; nothing is sent anywhere.

ParameterstorequiredxmlpdfBase64

parse_invoice

Parse an e-invoice into JSON

Reads an e-invoice (CII, UBL, XRechnung or Peppol XML, or a Factur-X / ZUGFeRD PDF) into the structured invoice object that create_invoice accepts, with money in integer minor units. Use it to answer questions about a received invoice, to edit one, or to re-issue it with create_invoice. It does not check any rules, so use validate_invoice for that, and convert_invoice to change syntax directly. For a PDF, `visibleTotals` shows whether the totals printed on the page match the embedded XML, which exposes a tampered or mismatched PDF. A document it cannot read comes back as an error result with the reason. Runs locally.

ParametersxmlpdfBase64

get_country_requirements

E-invoicing requirements for a country

Looks up the e-invoicing rules for one country in a sourced dataset: B2G and B2B mandates for issuing and receiving, start dates, turnover thresholds, required formats and official sources. Use it before create_invoice to decide which format a buyer in that country needs, or to answer when a mandate applies. It says nothing about a specific invoice; use validate_invoice to check one. Covers BE, DE, ES, FR, IT, NL, PL. `conformoSupport` says per format whether this server can create, read and validate it. Entries marked unverified are not confirmed from an official source; say so. Information, not legal advice. Reads a bundled dataset; no network.

Parameterscountryrequired

explain_validation_rule

Explain a validation rule

Explains one validation rule id, such as BR-CO-15, BR-DE-15, PEPPOL-EN16931-R003 or BR-FR-05: the publisher's official wording from the compiled rule sets and, where available, a plain-language summary, the reason for the rule and how to fix it. Use it after validate_invoice reports a rule you need to explain or fix, or when a user asks what a rule means. It does not check an invoice; call validate_invoice for that. An unknown id is not an error: the result has `found` false and an empty `official` list; say so and do not guess. Reads the bundled rule sets; no network.

ParametersruleIdrequired

Version history

3
  1. v0.2.3LatestNov 6, 2026
  2. v0.2.2Nov 5, 2026
  3. v0.2.1Nov 5, 2026

Score

90% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts
  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts