E-Invoice API for Developers

Validation, error analysis, and DATEV export via REST API — with TypeScript SDK, structured errors, and bilingual documentation.

API Documentation open_in_new Install SDK

Authentication

API key authentication

Every request is authenticated with a Bearer token. Create an API key and include it in the Authorization header.

terminal cURL

$ curl -X POST https://invoicekit-api.fly.dev/v1/validate \
  -H "Authorization: Bearer ek_live_..." \
  -H "Content-Type: application/json" \
  -d '{"xml": "<Invoice>...</Invoice>"}'

API Endpoints

Three endpoints. One API key.

Validation, batch validation, and DATEV export — every endpoint returns structured JSON responses with bilingual error messages.

check_circle

Single Validation

Validate an XRechnung or ZUGFeRD invoice. Supports raw XML and base64-encoded PDFs.

POST /v1/validate

dynamic_feed

Batch Validation

Validate up to 100 invoices in a single request. Results returned in same order as input.

POST /v1/validate/batch

receipt_long

DATEV Export

Generate DATEV EXTF posting batch CSV from accounting entries. Compatible with DATEV Kanzlei-Rechnungswesen.

POST /v1/datev-export

TypeScript SDK

Integrate in minutes

Type-safe client for all endpoints — with full TypeScript definitions and automatic error handling.

npm description API Docs

terminal TypeScript

$ npm install @invoicekit/sdk

// Usage
import { InvoiceKit } from '@invoicekit/sdk';

const client = new InvoiceKit({ apiKey: 'ek_live_...' });

const result = await client.validate({ xml: invoiceXml });
if (!result.valid) {
  console.log(result.errors);
}