There's also Spleeter Web [1], a self-hostable version of a Spleeter web app. A fun little project I've been working on! I'm thinking of supporting additional models such as Demucs [2], which seems to perform better than Spleeter.

[1] https://github.com/JeffreyCA/spleeter-web

[2] https://github.com/facebookresearch/demucs