Spotify Web API exposes Spotify's catalog, user playback state, and audio analysis via REST. One particularly valuable surface is the audio features endpoint: every track has tempo, energy, valence, danceability, acousticness, and more as 0–1 scores — ready-made features for music recommendation systems.

There are two OAuth flows. Client Credentials Flow handles public-data calls (search, metadata) and is the simpler setup. Authorization Code Flow runs user consent and unlocks playlists, recently played, and playback control. The Web Playback SDK can stream Spotify audio inside a browser, but the user must be Premium and must accept Spotify's terms.

Rate limiting uses a sliding window; exceeding it returns 429 plus a Retry-After header. Batch operations (e.g. bulk track sync) need backoff logic. A few categories of data — lyrics, detailed listener demographics — are not exposed publicly; lyrics typically come from licensed partners like Musixmatch.