How to Build an AI Vocal Remover in Python with the StemSplit API (2026)

I needed to add vocal removal to an app last week without shipping a 300 MB Demucs model with the binary. The shortest path I found was StemSplit's API — three endpoints, one model (HTDemucs), and a free tier big enough to prototype on. This is the working tutorial I wish I'd had. Single file, batch, webhooks, and a Flask wrapper at the end. All copy-paste runnable. What You'll Learn ✅ How to remove vocals from any audio file in 5 lines of Python ✅ How the async job pattern works (upload → poll