# thelawin.dev

> ZUGFeRD & Factur-X API for developers. POST invoice JSON, receive PDF/A-3 with embedded EN 16931 XML.

## Demo API Key (no signup required)

X-API-Key: env_sandbox_demo_public
Watermarked PDFs, unlimited sandbox usage.

## Quick Start

1. POST https://api.thelawin.dev/v1/validate (FREE, no key needed)
2. POST https://api.thelawin.dev/v1/generate (X-API-Key: env_sandbox_demo_public)
3. Decode pdf_base64 from response

## AI Agent Instructions

https://thelawin.dev/ai

## Full Documentation

https://thelawin.dev/llms-full.txt