F-Droid is a community-maintained software repository for Android, similar to the Google Play store. The main repository, hosted by the project, contains only free libre software apps. Applications can be browsed and installed from the F-Droid website or client app without the need to register for an account. “Anti-Features” such as advertising, user tracking, or dependence on nonfree software are flagged in app descriptions. The website also offers the source code of applications it hosts, as well as the software running the F-Droid server, allowing anyone to set up their own app repository.
The app itself is trade-free, yet some applications are not, they don’t check it. Some apps might ask money, any kind of data, or place adverts
The applications that they recommend are not checked for being trade-free or not. Just for not collecting data and being secure. Some applications may ask users for currencies such as money, bitcoin, and the like. So pay attention to that.