Design your own Spotify

Intermediate50 minBuilds Music Streaming ServiceRead first: 13.3 CDNs and media delivery, 7.1 Why caches work, 21.3 Stream processing

STEP 1 OF 11

The brief

You are designing a music streaming service. Listeners search a catalog, open albums and playlists, and press play. The track should start almost at once, even on a phone on a train, and every play has to be counted, because artists are paid per stream.

How big it is

Tracks in the catalog: about 100 million
Concurrent listeners at peak: about 30 million
Metadata and playlist reads: 20,000 / second
Play events: 2,000 / second
p99 goal for API requests: under 200 ms

The read rate counts API requests for track, album and playlist pages. Audio bytes are a separate, much larger flow: a listener downloads a few megabytes per song, in chunks.

What makes it tricky

Two very different read paths. Metadata is tiny and requested constantly; audio is large, immutable and streamed for minutes.
Popularity is skewed. A small share of tracks gets most of the plays, and a big release makes one album hot overnight.
Plays are money. Each one must be recorded durably, counted once, and never slow down playback.

All changes saved

0 components · 0 connections

A blank canvas. A better system.

Add components from the palette, then drag between them to connect the request and event flow.

React Flow

Design your own Spotify

Intermediate50 minBuilds Music Streaming ServiceRead first: 13.3 CDNs and media delivery, 7.1 Why caches work, 21.3 Stream processing

STEP 1 OF 11

The brief

How big it is

Tracks in the catalog: about 100 million
Concurrent listeners at peak: about 30 million
Metadata and playlist reads: 20,000 / second
Play events: 2,000 / second
p99 goal for API requests: under 200 ms

The read rate counts API requests for track, album and playlist pages. Audio bytes are a separate, much larger flow: a listener downloads a few megabytes per song, in chunks.

What makes it tricky

Two very different read paths. Metadata is tiny and requested constantly; audio is large, immutable and streamed for minutes.
Popularity is skewed. A small share of tracks gets most of the plays, and a big release makes one album hot overnight.
Plays are money. Each one must be recorded durably, counted once, and never slow down playback.

All changes saved

0 components · 0 connections

A blank canvas. A better system.

Add components from the palette, then drag between them to connect the request and event flow.

React Flow