LMMS - Make music with a free, cross-platform tool
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
Reaper - Reaper is a focused digital audio workstation (DAW) developed by Cockos. In the creation of the software, the digital audio technology company intended to make audio editing accessible to the masses.
AudioKit Synth One - Free & Open-source iPhone/iPad Synth 🎹
Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
FL Studio Mobile - Create & save multi-track music projects on a smartphone