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Geierlein is a free (AGPL’ed) Elster client, i.e. an application that allows to send VAT declarations to Germany’s fiscal authorities.

It’s a complete rewrite of its predecessors libgeier & Taxbird. Opposed to these it’s completely written in JavaScript and HTML5, hence it should be rather platform independent. From this it also follows that no compilation whatsoever is needed to get Geierlein to run.

Currently it is not possible to send returns that are due annually (especially the income tax return) since the fiscal authority doesn’t allow to do that off the ERiC library (which is proprietary however). It’s not clear at the moment whether one day it will be possible to do so.

Supported Interfaces

• XUL Desktop Application
• Node.js Command Line Interface
• Web Application using reverse proxy
  • Geierlein can be hosted on any web server that supports proxying with TLS client certificates like Nginx. The proxy access to the fiscal authority’s server is needed because of the browser’s XSS protection. Your data is encrypted on client-side no matter what, that is your sensitive data is in no case sent in any way not solely decryptable by the fiscal authorities.
  • Nginx Configuration