Getting Started with Postscale Invoices

Postscale Invoices lets you validate, send, and receive structured e-invoices (XRechnung, ZUGFeRD) through a simple API. Whether you need to check compliance before submission or deliver invoices directly via email, this guide covers everything to get started.

Prerequisites

A Postscale account with an active plan
An API key (create one at Dashboard > API Keys)
A verified domain (required for sending invoices)

Quick Overview

Capability	Endpoint	Description
Validate	`POST /v1/invoices/validate`	Check an XML invoice against EN 16931 / XRechnung rules
Send	`POST /v1/invoices/send`	Generate and deliver a compliant e-invoice via email
Receive	Inbound webhook	Automatically detect and extract e-invoices from incoming email

Your First Validation Call

The fastest way to try the API is to validate an existing invoice XML:

curl -X POST https://api.postscale.io/v1/invoices/validate \
  -H "Authorization: Bearer ps_live_..." \
  -H "Content-Type: application/xml" \
  -d @invoice.xml

A successful response looks like:

{
  "valid": true,
  "format": "xrechnung-ubl",
  "standard": "EN 16931",
  "errors": [],
  "warnings": []
}

If the invoice has issues, the errors array will contain detailed descriptions with field paths and rule IDs so you can fix them programmatically.

Next Steps

Validation API Reference — full request/response details, error codes, and examples
Sending E-Invoices — generate and deliver XRechnung invoices via the API
Inbound Processing — automatically detect e-invoices in incoming email
XRechnung Reference — formats, field mapping, and compliance notes