POST /v1/einvoice/convert · 1 cent per operation

Convert XRechnung between UBL and CII

Convert an XRechnung or EN 16931 invoice between UBL and CII (also from a ZUGFeRD PDF). Only valid invoices; the result must pass KoSIT and map back to the same fields.

Try it

curl -X POST https://api.bigapi.dev/v1/einvoice/convert -H 'Authorization: Bearer $KEY' -F 'file=@xrechnung-ubl.xml' -o xrechnung-cii.xml

New keys come with 100 free operations, no signup: curl -X POST https://api.bigapi.dev/v1/keys. Failed calls cost nothing.

Parameters

Name	Meaning
`file` required	E-invoice as XML (XRechnung UBL or CII, ZUGFeRD/Factur-X XML) or as PDF with an embedded invoice XML (ZUGFeRD, Factur-X, XRechnung hybrid).
`to`	Target syntax: cii (UN/CEFACT) or ubl. Leave empty to get the other syntax of the input. Allowed: `cii`, `ubl` Default: the other syntax

Result and price

1¢ · 1 cent per operation

Returns application/xml. Response headers carry the cost (X-BigAPI-Cost) and notes about your input (X-BigAPI-Warnings).

Good to know

The result must pass the KoSIT check and map back to exactly the same fields as the original. Otherwise there is no file.

Errors your agent should handle

`400 same_syntax`	The invoice already has the target syntax.
`422 invoice_invalid`	Invalid invoices are not converted; fix them first.
`422 unsupported_profile`	Profiles outside EN 16931 (BASIC WL, MINIMUM, ZUGFeRD 1.0) are not converted.
`422 convert_lossy`	A field would be lost or changed; you get no file.

From an agent (MCP)

Connect BiGapi as an MCP server: https://api.bigapi.dev/mcp (hosted) or npx -y @bigapi/mcp (local). Then ask in plain words; the agent finds einvoice_convert on its own.

I need this invoice as UBL instead of CII.

More: all guides · API docs · llms.txt