F-droid is available from
“F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
“F-Droid is a robot with a passion for Free and Open Source (FOSS) software on the Android platform. On this site you’ll find a repository of FOSS apps, along with an Android client to perform installations and updates, and news, reviews and other features covering all things Android and software-freedom related.” -F-droid.org