There are many alternatives to Caustic for Linux and since it's discontinued a lot of people are looking for a replacement. The best Linux alternative is LMMS, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Caustic and nine of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Caustic are Reaper (Paid), Tracktion (Freemium), Rosegarden (Free, Open Source) and SunVox (Freemium).
SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker). It is a tool for those people who like to compose music wherever they are, whenever they wish. On any device.
Waveform is a commercial, cross-platform DAW and spiritual successor to Tracktion . With a focus on design and composition, it offers tools to greatly simplify everything from initial inspiration to the final mix.
Bosca Ceoil is all about looping, and designed that way at its heart. Songs are built up from lots of tiny 16 note patterns – the intended workflow is that you loop over these single patterns until you have something you like, then you start making variations.