id Software LLC () is an American video game developer based in Richardson, Texas. It was founded on February 1, 1991, by four members of the computer company Softdisk: programmers John Carmack and John Romero, game designer Tom Hall, and artist Adrian Carmack.

id Software made important technological developments in video game technologies for the PC (running MS-DOS and Windows), including work done for the Wolfenstein, Doom, and Quake franchises at the time. id's work was particularly important in 3D computer graphics technology and in game engines that are used throughout the video game industry. The company was involved in the creation of the first-person shooter (FPS) genre: Wolfenstein 3D is often considered to be the first true FPS; Doom is a game that popularized the genre and PC gaming in general; and Quake was id's first true 3D FPS.

On June 24, 2009, ZeniMax Media acquired the company. In 2015, they opened a second studio in Frankfurt, Germany.