Most Spotify taps never touch the network

transcript

You tap a song on Spotify. Music in under 200 milliseconds. Most of the time, your phone didn't even ask the internet.

The obvious player: tap, ask the backend, fetch the file, play. Every tap pays a trip to the backend, then storage. That alone can eat 200 milliseconds. Check rights on every audio request? Now the backend carries every byte. Write the play event first? Analytics delays the first note.

First question: is the song already on your phone? For most taps, yes. Recently played, downloaded, or prefetched during the last song. If not, a CDN edge nearby. The top 20 percent of songs are always cached there. Only a long-tail miss reaches the origin.

But who checks you're allowed to play it? The backend. Once. It hands back a signed URL, good for one hour. The edge checks that token itself. No backend call. And a leaked link stops working within the hour.

And the note that you played it? It leaves your phone later. Fire and forget. Events never block the music.

Nothing slow sits on the play path. The fastest fetch is no fetch. The next fastest is an edge near you.

Full breakdown in the lecture.