Zrythm
(in development/unstable)(GNU Affero General Public License)
Zrythm is a digital audio workstation designed to be featureful and easy to use.
It allows limitless automation through curves, LFOs and envelopes, supports multiple plugin formats including LV2, VST2 and VST3, works with multiple backends including JACK, RtAudio/RtMidi and SDL2, assists with chord progressions via a special Chord Track and chord pads, and can be used in multiple languages including English, French, Portuguese, Japanese and German.
Zrythm is free software written in C using the GTK+3 toolkit.
Give it a try!