BandLab
A genuinely free cloud DAW — real multitrack recording, not a stripped demo.
BandLab is a browser-based digital audio workstation built on the old Cakewalk/SONAR codebase, and unlike most "free" music software, the core Studio isn't a trial or a limited tier — it's actually free, which their own homepage leads with rather than burying. Good enough that it's genuinely used for finished releases, not just demos.