BeInX is described as 'Lightweight, open-source application designed to create, manage, and export simplified e-invoices for freelancers in compliance with the XRechnung and ZUGFeRD standards. It runs locally and completely offline as Progressive Web App (PWA)' and is an website. There are four alternatives to BeInX, not only websites but also apps for a variety of platforms, including iPhone, iPad, Apple Watch and SaaS apps. The best BeInX alternative is Billings Pro. It's not free, so if you're looking for a free alternative, you could try Unlimited Invoices or Tinyinvoice.com.