When Spotify deprecated audio_features and audio_analysis, the obvious loss was the per-track numbers — tempo, key, energy. The quieter loss was everything you used to build on top of them: the "what should I play next" logic, the harmonic-compatibility checks, the auto-ordered playlist. Plenty of people have written a host-swap guide to get the raw fields back. This post is about the layer above that — turning a crate of track names into an actual, beat-matched, key-compatible set.
We'll do it in about 50 lines of Python against the FreqBlog Music API, using four endpoints: /next-track (what mixes well after this?), /transition (how well do these two mix, exactly?), /setlist (order this whole crate into an energy arc), and /export/rekordbox (drop the result straight into Rekordbox or Serato). No audio files, no Spotify ID — you pass track names or catalog IDs.
New here? If you haven't migrated off Spotify's removed endpoints yet, start with Spotify Audio Features Is Dead. Here's What to Use Instead in 2026 for the landscape and the host swap, then the field-by-field threshold guide to re-tune your numbers. This post assumes you can already get a track's key and BPM and want to build set logic on top.
