Musicolet - Musicolet is a small yet feature-rich offline Music Player for Android.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Palco MP3 - Palco MP3 is the largest Brazilian application for independent artists and offers more than 1 million songs for you to listen and download on your mobile device.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Audiomack - The free SoundCloud alternative
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.