What Spotify Lets a Client Do

Spotifast uses Spotify’s Web API for account and catalogue data. It uses librespot for a few extra details and for audio playback.

Features missing from both cannot be added to Spotifast. They may become possible if Spotify adds an API or librespot adds lawful support.

Web API

Spotifast uses the Web API for:

  • Account: profile details, followed artists, top artists and tracks, and the last fifty plays. Spotifast keeps a longer local history.
  • Library: playlists, saved tracks, albums, shows, and episodes. It can also save and remove items.
  • Playlists: reading, creating, renaming, changing the description and visibility, adding and removing songs, reordering songs, and following and unfollowing. The API also supports cover uploads, but Spotifast does not yet use them.
  • Catalogue: albums, artists, tracks, shows, episodes, search, and recommendations. Artist pages include top tracks, releases, and related artists.
  • Playback control: listing devices, transferring playback, play, pause, next, previous, seek, shuffle, repeat, volume, and reading or adding to the queue.

Users of the default app share Spotify’s quota. Spotifast limits heavy requests and pauses a session when Spotify sends a Retry-After response.

Spotify also limits apps created since November 2024. These apps cannot access Spotify-owned playlists, related artists, recommendations, or audio features. This is why a personal app cannot handle every request. Complete playlist library views stay on the shared app. Playlists other people own, and every playlist when there is no personal app, are read over the librespot session while local playback is signed in. See How It Connects.

librespot session

librespot signs in to Spotify and uses the same protocol as Spotify’s own clients. Spotifast uses its session for:

  • Playlist folders and order. Spotifast can read them from Spotify’s rootlist. librespot cannot create, rename, or move folders.
  • Playlist permissions. The rootlist shows when a playlist shared by invitation can be edited. The Web API’s collaborative flag does not cover these playlists. Spotifast cannot manage collaborators.
  • Playlists the shared app would otherwise serve. Title, cover, and songs of other people’s playlists, and of the account’s own when there is no personal app, so they open without the shared app’s quota. Whether a playlist is public, the owner’s name when the session gives none, and the mosaic of a playlist without a cover of its own, come from the Web API’s library list. These rows carry no per-market availability flag. A song the Web API had already greyed out, on an earlier page or in the cache of an earlier visit, stays greyed out when the session reads the rows. This knowledge belongs to the signed-in account, and a newer Web API answer takes precedence over an older disk cache. A song the session reads first has unknown availability; if it cannot play, it is skipped when reached, as it would be anywhere else.
  • Lyrics when Spotify has them.
  • Display names for the user IDs attached to songs in a playlist.
  • Precise EP types for releases that the Web API groups with singles.
  • Song radio and autoplay through Spotify’s context resolver.

librespot playback

librespot provides:

  • Spotify catalogue playback at up to 320 kbps.
  • Gapless playback, normalisation, and a local audio cache.
  • Spotify Connect, so another Spotify client can transfer playback to this computer.
  • Shuffle, repeat, seek, and volume.
  • Songs and podcast episodes.

Spotify Premium is required. librespot cannot play audio with a free account.

Spotifast uses a small librespot fork. Its patches add queue controls, normalisation data for the visualisers, and an event for rejected audio keys. They are listed in Cargo.toml. Larger changes go upstream first.

Not available

The Web API and librespot do not provide these features:

  • Pins shared with the Spotify app. Spotify stores pins in its private your-library service. There is no Web API for it, and librespot does not support its protocol. Spotifast’s pins are local and are stored in settings.json. See issue #31.
  • Editing playlist folders. librespot can only read them.
  • Smart Shuffle, Jam, Blend, and similar Spotify features. Spotify generates these for its own clients. Spotifast only has plain shuffle.
  • Lossless audio. librespot does not receive lossless streams. Spotifast will reconsider this if librespot gains lawful support, but it will not bypass Spotify’s DRM.
  • Local files. librespot only streams Spotify’s catalogue. It cannot fetch audio for a spotify:local: entry. Playing files from disk would require a separate player. See issue #3.
  • Audiobooks. librespot does not play them.
  • Offline listening and downloads. Spotify’s DRM and the project’s scope rule these out.
  • Playback speed and crossfade. librespot supports neither. Spotifast would have to add them to its own audio path.
  • Free-account playback. Replacing Spotify audio with another source is also out of scope. See the contribution guide.
  • Friend activity, private-session status, and similar social features. Spotify has no public API for them.
  • Canvas videos and video podcasts. librespot does not provide them.