tl;dr: StemDeck is a free, open-source desktop app that runs Meta's Demucs (htdemucs_6s) locally to split audio into up to 6 stems (vocals, drums, bass, guitar, piano, other) from local files or YouTube URLs. It includes a DAW-style multitrack mixer with waveform editing, looping, per-stem controls, VU meters, BPM/key detection, and LUFS analysis, with GPU acceleration via CUDA or Apple Silicon MPS. Built with FastAPI, Tauri v2, and vanilla JS, it ships as macOS DMGs, Windows zips, or Docker images as a local alternative to cloud services like Moises and LALAL.AI.