How Spotify tracks play

MixMusic plays Spotify tracks three ways: in MixMusic through Spotify's own player, on Spotify Connect, or from their recording on YouTube Music.

You choose the way in Settings › Playback › Spotify tracks. Each needs a Spotify sign-in, made with a Spotify app of your own: Spotify walks you through it, and tells what to do when Spotify refuses the sign-in. For the code, read the player's part of the architecture and its web views.

The three ways at a glance

When the way you chose can't play a track, as when no device answers or Spotify can't play in MixMusic, the track plays from YouTube Music instead, and MixMusic says why once. A Spotify track always downloads as its recording on YouTube Music, whatever the way, and while you're offline it plays from its download or the offline cache that way.

In MixMusic, from YouTube Music

MixMusic finds the track's recording on YouTube Music, by its title, its artists and its length, and plays it in its own engine, with everything the audio engine does. The listener needs no Premium. This way is called Match in settings.json and in the code.

How the match is made:

1. The search. MixMusic searches YouTube Music's songs for the title and the first artist, and when none is close enough, its videos.
2. The score. Each result scores from 0 to 1:
   • 45% for the title: the share of the words of the shorter title that the other has, once both are in lower case, without accents and punctuation, and without what names a release rather than the song, as "(Remastered 2011)", "- Radio Edit" or "[Official Video]";
   • 35% for the artists: one of the track's artists is the result's, or its title names them, as uploads called "Artist - Song" do;
   • 20% for the length: within 2 seconds counts whole, within 5 seconds 0.8, within 10 seconds 0.5, within 20 seconds 0.2, and beyond that nothing; half when either length isn't known;
   • and 0.05 more for a song over a video, as songs are the released recordings.
3. The choice. The best result plays when it scores 0.6 or more. Otherwise YouTube Music has no recording close enough, and the track can't play this way.
4. The memory. MixMusic keeps each match in matches.json in its cache folder, so a track is searched for once.

When a match is wrong, choose Find another YouTube Music match in the track's menu: the next play searches again, and a track you downloaded downloads again as its new match.

In MixMusic, from Spotify

MixMusic plays the track itself, with Spotify's own player, at Spotify's quality, with no Spotify app open. It needs Spotify Premium, and Windows.

• How. Spotify's Web Playback SDK, which MixMusic loads from sdk.scdn.co, plays Spotify's protected audio in a hidden window of a page of MixMusic's own. Only WebView2, the web view of Windows, decrypts that audio: WebKitGTK on Linux doesn't, and macOS's web view isn't known to, so this way is greyed out there.
• A device of its own. The page makes MixMusic a Spotify Connect device, named MixMusic, which shows among your Spotify devices while it plays. MixMusic plays tracks on it through the Web API, as on any device, and follows it by asking the page, which tells at once when its track changes. The window opens at the first Spotify track that plays this way, and closes when you sign in again or change the setting.
• Your sign-in. Playing Spotify in MixMusic needs a permission that sign-ins made before 0.5.0 lack: Settings › Playback asks you to sign in again, and until you do, Spotify tracks play from YouTube Music.
• The sound. Spotify's player plays at your volume, on the same curve as MixMusic's own. The equalizer, crossfade, Even loudness and speed don't reach it: Spotify keeps its own loudness and speed. On Windows 10 build 20348 and later, the visualizer hears it through Windows' process loopback.

What 0.5.9 changed

• Songs follow one another without a gap. MixMusic gives Spotify the track with up to 20 of the Spotify tracks the queue moves on to after it, turns the device's shuffle and repeat off so that it plays them in the queue's order, and Spotify goes on to each by itself. Between 1 and 2 seconds of silence came between them before (#187).
• A YouTube Music track after a Spotify one starts at once, as MixMusic hears the moment Spotify's song ends. When the queue changed meanwhile, as when you chose Play next, what Spotify went on to is silenced, and the song you chose plays (#187).
• A seek into a song's last seconds no longer leaves a gap or skips a song of the queue. Spotify stops on the song a moment while it loads the next: MixMusic now gives it up to 2 seconds to go on before it plays the next track itself (#273).
• A track plays once you hear it. Spotify says a track plays about 0.3 seconds before its sound starts. Until it sounds, or for 10 seconds at most, the track loads: it can't be paused or moved, so a click can't start its load over (#184).

On Spotify Connect

A Spotify device plays the track: the Spotify app on this computer, your phone, a speaker or a TV. It needs Spotify Premium, and a device with Spotify open.

• Which device. Settings › Playback › Spotify tracks › Device, or the devices button of the player bar, chooses it; by default, the active device. Open Spotify on a device for it to show there.
• How MixMusic follows it. MixMusic sends the device commands through the Web API, asks it what it plays every 3 seconds, and moves the progress on each second between. Spotify's reports lag its commands by a few seconds, and may name the track by the ID of the copy Spotify plays in your country, so MixMusic waits for the device to settle, and knows a track by more than its ID.
• The queue stays in MixMusic, which tells the device to play the next track as one ends.
• The visualizer hears the Spotify app on this computer, on Windows; other devices it can't hear, and it draws nothing then.
• Sleep. As the computer goes to sleep, MixMusic pauses its own player, and a device elsewhere plays on.

Premium and development mode

Spotify keeps apps that it hasn't reviewed in development mode, and every MixMusic user signs in with such an app, made in two minutes on Spotify's developer dashboard. Spotify limits these apps, more so since February 2026:

• The app's owner needs Premium, or Spotify refuses every sign-in with the app. The other accounts need Premium only to play Spotify's own audio, in MixMusic or on Spotify Connect: without it, their Spotify tracks play from YouTube Music.
• Five users. Up to five Spotify accounts, added under Users Management in the app's settings, can sign in with it. To let a friend in, add them there, or have them make an app of their own.
• Smaller answers. A search gives at most ten results of each kind; the app sees the tracks of the playlists you own or collaborate on, not of playlists others made, which MixMusic tells you; Spotify gives no artist's top tracks, which MixMusic finds with a search instead; and shows come without their publisher.
• A quota. When MixMusic makes too many requests, Spotify asks it to wait, and MixMusic says so.

Podcast episodes

Spotify's podcast episodes play only from Spotify, in MixMusic or on Spotify Connect: YouTube Music has no recording of them, so the YouTube Music way doesn't play them, and says so.

• Where you left them. MixMusic keeps where you left each episode, and starts it 5 seconds before. An episode you never played in MixMusic starts where Spotify says you left it, as on your phone. That takes a permission sign-ins made before 0.5.9 lack: sign in to Spotify again for it.
• What's different. Episodes don't crossfade, play at Spotify's own speed, and don't scrobble. A search asks Spotify for ten shows and ten episodes.