The goal of this project was to research and develop a service platform where users can compete others in their outdoor activities. To that end a user records a challenge with his smartphone and publishes it together with a specification ot the challenge (e.g. distance, time, type of activity) and the achievements to be gained, when other users successfully pass the challenge. Other users can accept the challenge and record his performance in the challenge with the corresponding app that monitors the criteria of the challenge.