Gci
Google Code-in is an annual contest that introduces pre-university students ages 13 to 17 to the world of open source development. With a wide variety of bite-sized tasks, it’s easy for beginners to jump in and get started no matter what skills they have.
We're considering joining this effort in partnership with The MetaBrainz Foundation for the mutual benefits it would provide: sharing of Mixxx users' careful metadata with the wider community (with opt-in) and time savings when Mixxx users add new tracks to their databases that already exists in the MetaBrainz databases.
This is the Mixxx Wiki - 
Mixxx is a free and open-source DJ software.
Manual
Hardware Compatibility
Reporting Bugs
Getting Involved
Contribution Guidelines
Coding Guidelines
Using Git
Developer Guide
Creating Skins
Contributing Mappings
Mixxx Controls
MIDI Scripting
Components JS
HID Scripting