Spotify's stack: audio delivery + recommendations + social features. Cassandra + Kafka + Storm + BigQuery. Discover Weekly built here.

Client (App)Player APITrack ServiceDiscovery / RecsPlaylist ServiceSocial GraphAnalyticsAudio CDNOGG VorbisCassandraplaylists + likesBigQuerylistening eventsML ModelsDiscover Weekly
Spotify: audio CDN + recs + Cassandra playlists + BigQuery analytics + ML for Discover
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Audio delivery

OGG Vorbis encoded at multiple bitrates. Served from CDN. Adaptive quality based on connection.

Audio delivery

OGG Vorbis encoded at multiple bitrates. Served from CDN. Adaptive quality based on connection.

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Discover Weekly

Weekly playlist per user, generated Sunday nights. Collaborative filtering + audio analysis + NLP on artist metadata.

Kafka event pipeline

Every play, skip, like, save → Kafka. Powers real-time recs + billing (royalties) + analytics.

Cassandra for user data

Playlists, likes, listening history. Multi-DC. Massive scale — trillions of rows.

Social features

Follow friends, see their listening. Small overlay on core music delivery. Uses graph service.

Audio CDN + Kafka events + Cassandra user data + ML for Discover. Music streaming as a data problem.