bismark CtrlSlide – MIDI CC is free on Google Play

bismark CtrlSlide – MIDI CC is an Android app from bismark that normally costs $1.99 on Google Play and is currently free. As its name suggests, it focuses on MIDI CC (control change) messages, so you can use your phone or tablet as a control surface for your music setup.

It's best suited to musicians, producers and hobbyists who work with MIDI gear or software and want a handy controller on an Android device. If you never use MIDI, you can skip this one, but it costs nothing to try.

No end date has been given, so claim it soon. Paid Google Play apps you get while they're free usually stay linked to your Google account, so you should be able to reinstall it later from your library after the price goes back up.