Convert PDF to CII using REST-API

Convert a PDF invoice into a standalone UN/CEFACT Cross Industry Invoice (CII) XML document. CII is the XML syntax that underpins both ZUGFeRD and Factur-X and is one of the two official syntaxes of the European EN 16931 standard.

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POST https://api.invoicexml.com/v1/transform/to/cii

Request

Parameter	Type	Description
file *	binary	The PDF invoice file to convert.
strict	boolean	Defaults to `false`. When `true`, treat validation warnings as errors — the request is rejected if any warning is raised, not just errors.
version	string	Standard version (e.g. `2.3.2`). Defaults to the latest supported version.
profile	string	Compliance profile. Values: `minimum`, `basicwl`, `basic`, `en16931`, `extended`. Defaults to `en16931`.
syntax	string	XML syntax: `cii` (Cross Industry Invoice) or `ubl` (Universal Business Language). Defaults to `cii`.

Content-Type: multipart/form-data

Headers

Header	Value
Authorization *	Bearer YOUR_API_KEY
Content-Type	multipart/form-data

Response

200 Returns the CII XML document.

Content-Type: application/xml

Code Example

curl -X POST https://api.invoicexml.com/v1/transform/to/cii \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "[email protected]" \
  -F "version=2.3.2" \
  -F "profile=extended" \
  -F "syntax=cii"

Frequently Asked Questions

What is CII?

CII (Cross Industry Invoice) is an XML schema maintained by UN/CEFACT. It is one of the two syntaxes allowed by the European e-invoicing standard EN 16931 — the other being UBL 2.1.

When should I use CII instead of UBL?

CII is the default syntax for ZUGFeRD and Factur-X invoices. Use CII when your trading partners or national regulations (e.g., Germany, France) expect CII-based documents.

Is the output embedded in a PDF?

No. This endpoint returns a standalone CII XML file. If you need the XML embedded inside a PDF/A-3, use the /v1/transform/to/facturx or /v1/transform/to/zugferd endpoints instead.

Is the XML validated?

Yes. Every generated CII document is validated against EN 16931 Schematron business rules before delivery to ensure compliance.

What CII version is used?

The API generates CII D16B (the version referenced by EN 16931), ensuring compatibility with all European e-invoicing infrastructure.