F-Droid

F-Droid is an app store for Android that lists only software whose source code is available. It is installed as an app of its own rather than coming with the phone, and it can install, update and remove the applications it lists.

What distinguishes it from other stores is that the packages are built from source by the project rather than uploaded by the developer, and each listing carries notes about behaviour a reader may want to know before installing — whether the app tracks usage, depends on a proprietary service, or shows advertising. Those notes are part of the catalogue data, not a rating.

The catalogue is a repository, and the app can be pointed at additional repositories besides the main one, which is how projects distribute builds that are not in the default list.