F-Droid

F-Droid is a free and open source app store and software repository for Android, serving a similar function to the Google Play Store. The main repository, hosted by the project, contains only free and open source apps. Applications can be browsed, downloaded, and installed from the F-Droid website or the client app without registering an account. "Anti-features" such as advertising, user tracking, or dependence on non-free software are flagged in app descriptions.

Excerpt from Wikipedia: F-Droid. Content available under CC-BY-SA 4.0.