Couleurbummel is a free travel and navigation app developed by Björn Marschollek. It is designed to guide users to different fraternity houses in various cities in Germany, Austria, and Switzerland. This app is particularly useful for active or pledge trips, as it eliminates the need to carry around paper city maps with poorly marked fraternity houses.

The app requires three permissions: internet access, location services, and phone call capabilities. The latter permission is solely for the purpose of allowing users to call a selected fraternity house directly from the app. Currently, the app lists 1247 fraternities in 147 college towns. It offers support for several cities in Germany, Austria, and Switzerland, including Aachen, Berlin, Graz, and Zurich.

Couleurbummel started as a project for the developer's own fraternity in Aachen, Germany, and quickly expanded due to its popularity. The app is available for both Android and iPhone and is completely free and ad-free. It also includes a donation button for users who wish to support the developer's efforts. Overall, Couleurbummel is a convenient and practical app for fraternity members and those interested in European-style fraternities.