Xataka Android we have already spoken of app stores where developers can publish their creations and get benefits, or not, with the downloads that users make. However there are developers who are usually not in accordance with the rules of the game imposed, by active and passive, the different services.
For them there is F-Droid, a repository where people not only share their applications but also the source code so any programmer can improve it or adapt it to your needs. All distributed through a FOSS license (free and open source software).
Once you have installed the application in your terminal can access to the application of the repository list. Unlike for example the Android Market or the Amazon App Store you can select which version of the application we want to download. An option frankly very useful both for users of a foot as developers.
Also, as we mentioned, you can download the source code of the application and subsequently upload a new revision to the repository of F-Droid. Of course respecting the FOSS license which it has distributed originally.
F-Droid It is a free application as well as the content published on it. However, if we want to collaborate with the project creators accept donations to help them economically.