A GPD file is a gamer profile data file used by Xbox 360 to store information about a user, including his settings, games played, achievement records for each game played, and any achievement images. It is saved in the Xbox Database Format (XDBF), which is a container format for storing Xbox files and records. GPD files are generated from Statistics, Presence, and Achievement (SPA) files embedded in game bundles when a user plays the game.

You can mod a game by editing the GPD file associated with the game, commonly Black Ops or Borderlands 2. This allows you to unlock gameplay features you previously did not have. To replace or inject a GPD file, move your profile from an Xbox 360 HDD to a USB flash drive and connect the drive to a computer running Windows with the Horizon or Modio modding tools installed: If you are using Horizon, select "Device Explorer" and navigate to the Gamer Profiles folder on your flash drive. You can then right-click your profile, select Extract File..., and choose the save location. Then drag and drop your profile onto the open grey area, which opens the "Package Manager" tool. Click the "Contents" tab to view all of the GPD files within your profile. If you are using Modio, click the "M" logo in the top-left corner and select "Explore my Device." In the Device Explorer window select File → Open/Close Drive and navigate the file tree to your profile. You can drag and drop the profile onto your desktop then drag it back to Modio and drop it on the open area. The "Profile" window will open where you can then select the "File Contents" tab to view all of the GPD files within your profile. Each game has a unique title ID used to name its correlating GPD file. The filename is a a sequence of numbers and letters. You can open the GPD file with a hex editor, such as HxD or HEXplorer, and edit the hex code.