Google Play Music Desktop Player provides an interface for external applications to determine the currently played song and playback status.

The interface is provided through a file that is continuously updated, allowing external applications to watch the file to always have the current playback information. The file is JSON-formatted and located at:
- Windows: %APPDATA%\Google Play Music Desktop Player\json_store\playback.json
- OS X: ~/Library/Application Support/Google Play Music Desktop Player/json_store/playback.json
- Linux: ~/.config/Google Play Music Desktop Player/json_store/playback.json

Data Format

The file contains a single JSON object with the following attributes:
- playing: (bool) Whether or not the player is current playing. This is false when the player is closed.
- song: (object) A song object in the format below.
- time: (object) A time object in the format below.
- songLyrics: (string) The full lyrics of the current song, or null if we could not find the lyrics
- shuffle: (string) The current shuffle mode (Values can be found here)
- repeat: (string) The current repeat mode (Values can be found here)

Song Object

All attributes are null if no song is playing. If a song is paused the variables are set correctly.
- title: (string) Title of the song
- artist: (string) Artist of the song
- album: (string) Album of the song
- albumArt: (string) URL that points the Album Art

Time Object

All attributes are 0 of no song is playing. If a song is paused the variables are set correctly.
- current: (number) Number of milliseconds into the song we are
- total: (number) Total length of the song in milliseconds

Example

// Playing
{
  "playing": true,
  "song": {
    "title": "Trumpets",
    "artist": "Jason Derulo",
    "album": "Tattoos",
    "albumArt": "https://lh6.ggpht.com/J9gNObbLJ_R71OHy-F6ENINYlnjf6Hjx_dw4RV0GLSTH1zrDEFSeRcW_Kf2fTws0swmOXwot=s90-c-e100"
  },
  "rating": {
    "liked": false,
    "disliked": false,
  },
  "time": {
    "current": 4908,
    "total": 217000
  },
  "songLyrics": "Lyrics here :)",
  "shuffle": "ALL_SHUFFLE",
  "repeat": "LIST_REPEAT"
}

// Not Playing (Stopped)
{
  "playing": false,
  "song": {
    "title": null,
    "artist": null,
    "album": null,
    "albumArt": null
  },
  "rating": {
    "liked": false,
    "disliked": false,
  },
  "time": {
    "current": 0,
    "total": 0
  },
  "songLyrics": null
}