Blitz Chess Clock is a free Android app developed by Niklas Baudy that lets you play blitz chess games with your friends. The app supports normal blitz modes as well as Fischer modes, and comes with several pre-set modes including 1m, 1m + 1s, 3m, 3m + 3s, 5m, 15m + 10s, and 25m. You can also add your own time modes and the app can handle different times per player.

In addition to the time settings, Blitz Chess Clock offers a variety of clock themes to adjust the app to your environment. If you want even more customization, you can create your own themes. The app also supports different chess modes, including Bullet Chess, Rapid Chess, and Fischer Modus.

Overall, Blitz Chess Clock is a convenient and easy-to-use app for playing chess games with time. It can also be used for other games like Go.