Invoice as a Service vs eInvoicing

Simple invoicing REST API — send JSON, get a PDF

A dead-simple invoicing microservice. Send a JSON payload with your invoice data, get back a beautifully formatted PDF. No database, no accounts, no UI — just an API endpoint you can integrate into any stack. Self-hostable, Docker-ready, and perfect for developers who want programmatic invoice generation without a SaaS dependency.

Library for creating European-compliant electronic invoices

A PHP library for reading and creating electronic invoices compliant with the European EN 16931 standard. Supports Factur-X, ZUGFeRD, and UBL formats. If you sell to businesses in the EU and need to generate legally compliant e-invoices, this library handles the complex XML and PDF/A requirements so you do not have to.