FreqBlog Music Metadata
Audio features for real tracks by name, artist, ISRC or MusicBrainz ID - BPM, musical key (name + Camelot + Open Key), energy, danceability, valence, mood, genre and 40+ more fields. No Spotify ID and no audio upload needed, which makes it a drop-in for Spotify's removed audio-features endpoint. Also does harmonic mixing: score how well one track mixes into another, suggest the next track, and order a whole crate into a beat-matched setlist. Free to use, no signup.