Until AM - DJ in your browser with this SoundCloud music mixer
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Songlio - Free musical guessing game: race friends to name that tune
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Fretello Stage - Jam, record and share your music in the blink of an eye
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.