Helio Workstation by Peter Rudenko (@KVRAudio Product Listing): Helio is a lightweight free music sequencer for OS X, Linux, Windows, iOS and Android. Aimed to be a perfect sketching tool, Helio features high-performance core, linear-based sequencer with clean interface, integrated version control providing intelligent synchronization between devices, saved undo history, translations to many languages and more. And it's free and open-source. {See video at top ...