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Create a CII Invoice API

Test the CII REST API, submit your invoice details and download a validated UN/CEFACT CII D16B XML. EN 16931 Schematron-checked.

Have an existing invoice? Upload a PDF and we'll prefill the form
Invoice Details
Seller (From)
Buyer (To)

Invoice Automation Wherever You Work

Built for developers and AI-driven workflows. Make your invoices compliant on your ERP or AI Agent via our secure MCP server and REST API.

REST API

Full-featured API for developers. Integrate invoice conversion into any stack.

No-Code Platforms

Connect via NoCode platforms like Zapier, Make and n8n, no engineering required.

MCP for AI Agents

Let your AI agents validate and convert invoices autonomously via our MCP server.

For Developers
Developer API

Built for Developers

Submit invoice data as form fields, receive a validated UN/CEFACT CII D16B XML. ZUGFeRD and Factur-X embeddable, EN 16931 Schematron-checked.

  • Supports all formats: DOCX, XLSX, PDF, images, no preprocessing needed
  • Works on scanned and photographed invoices
  • Every response validated against official Schematron rules

Supports ZUGFeRD · Factur-X · XRechnung · UBL · CII · EN 16931

API Documentation
Terminal 
$ curl -X POST https://api.invoicexml.com/v1/create/cii \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: multipart/form-data" \
  -F "InvoiceNumber=INV-2025-001" \
  -F "IssueDate=2025-07-01" \
  -F "SellerName=Acme GmbH" \
  -F "BuyerName=ACME Corp"
// => 200 OK
// => { "id": "inv_8f3k...", "status": "completed" }

Beyond the Form: Automate Your CII Invoice Workflow

This form is perfect for one-off invoices. But if you generate dozens or hundreds of CII documents, for ZUGFeRD embedding, ERP integration, or e-invoicing network delivery, InvoiceXML gives you the tools to automate the full pipeline with a single API call or no-code trigger.

1. Developer-First REST API

Integrate CII generation directly into your ERP, accounting software, or custom application with a single HTTP call:

  • • Single Endpoint: POST your invoice fields as JSON and receive a validated UN/CEFACT CII D16B XML back instantly, ready for standalone delivery or PDF/A-3 embedding.
  • • Stateless & Secure: We process your data in memory and return the XML. No financial data is stored or logged.
  • • Full Compliance: Every generated CII document is validated against EN 16931 Schematron business rules before delivery, the same rules ZUGFeRD and Factur-X validators enforce.
  • • ZUGFeRD & Factur-X Ready: The output CII XML is structurally identical to the XML embedded in ZUGFeRD 2.x and Factur-X documents, attach it to a PDF/A-3 in your own pipeline or use our /create/zugferd and /create/facturx endpoints to get the full hybrid PDF in one step.

Pro Tip: Check out our API Documentation to see the full request schema and response format.

2. Email Gateway, Send JSON, Receive CII XML

The InvoiceXML Email Gateway requires zero API integration, any system that can send email can trigger CII generation:

  • • How it works: Email a JSON attachment containing your invoice data to your dedicated InvoiceXML gateway address. We generate the validated CII XML and email it back, ready for delivery or ZUGFeRD embedding.
  • • Legacy ERP Friendly: Any system with outbound email capability can trigger CII generation, no webhook setup, no API keys in your code, no infrastructure changes.
  • • Batch Support: Send multiple invoice objects in a single JSON array and receive all corresponding CII XML files in return.

3. No-Code Automation (Zapier, Make.com & n8n)

Connect InvoiceXML to the tools your team already uses, no developer required:

  • • ERP & Accounting: Trigger CII generation automatically whenever a new invoice is created or approved in your system, no manual export step.
  • • Google Sheets / Airtable: Turn a row of invoice data into a validated CII XML and forward it to your document management system or e-invoicing network automatically.
  • • ZUGFeRD Pipeline: Chain CII generation with a PDF/A-3 embedding step in Make.com or n8n to fully automate ZUGFeRD hybrid invoice production without writing a line of code.

Why UN/CEFACT CII Is the XML Backbone of European E-Invoicing

UN/CEFACT CII (Cross Industry Invoice) D16B is one of the two official XML syntaxes of the European EN 16931 e-invoicing standard. It is the format embedded inside every ZUGFeRD and Factur-X document, making it the most widely deployed structured invoice format in Germany and France. Beyond hybrid PDFs, CII is used as a standalone XML exchange format by ERP systems, accounting platforms, and e-invoicing networks across the EU and internationally.

FeatureOur CII Implementation
StandardEN 16931 + UN/CEFACT CII D16B
Output FormatStandalone CII XML (PDF/A-3 embeddable)
Schema VersionCII D16B (CrossIndustryInvoice)
Compatible FormatsZUGFeRD 2.x, Factur-X, standalone XML
ValidationEN 16931 Schematron business rules

Complete CII Toolkit

Everything you need to create, convert, validate, and preview CII invoices, via REST API or online.

Create CII API

Build a validated CII D16B XML from structured data, ready for ERP import or PDF/A-3 embedding.

Try it out

Validate CII API

Validate CII XML against CII D16B schema and EN 16931 Schematron business rules.

Try it out

PDF to CII API

Convert any PDF invoice into a standalone CII XML using AI extraction.

Try it out

Preview CII as PDF API

Render a CII XML as a human-readable PDF for review and approval.

Try it out

Frequently Asked Questions

No. We process your invoice data in memory and discard it immediately after the XML is generated and downloaded. Nothing is persisted.
Yes. The output is a fully validated CII D16B XML that is structurally identical to the XML embedded in ZUGFeRD 2.x and Factur-X documents. You can attach it to a PDF/A-3 using any compliant library. Alternatively, use the /create/zugferd or /create/facturx endpoints to get the complete hybrid PDF in a single API call.
Both are valid EN 16931 syntaxes. CII (UN/CEFACT) is the format used by ZUGFeRD and Factur-X hybrid PDFs, it is the dominant choice in Germany and France. UBL (OASIS) is the native format of the Peppol network and is used for B2G invoicing in Nordic countries, Singapore, and Australia. Choose CII when your recipient uses ZUGFeRD, Factur-X, or a CII-based ERP integration.
/create/cii returns a standalone CII XML file, ideal for ERP import, direct transmission, or manual PDF/A-3 embedding in your own pipeline. /create/zugferd returns a complete ZUGFeRD-compliant PDF/A-3 with the CII XML already embedded, ready for direct B2B exchange.
Yes. The InvoiceXML Email Gateway lets any system with outbound email trigger CII generation without API integration. Email a JSON attachment to your dedicated gateway address and receive the validated CII XML in reply.

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