chessendgametraining

Chess Endgame Training: app to practice a variety of well organized set of chess endgames. From elementary to the most complex endgames, you can practice until you learn how to face all of them. Maintained by supertorpe on GitHub, where it has earned 152 stars from the community.

It's actively developed around chess, app, android, and is a solid reference for anyone building with these tools.