Third-party software has been indispensable for building Grand Theft Auto mods, due to the lack of official editing tools from the developer, Rockstar Games. Frequently created by anonymous ' modders', modifications are presented in the form of downloadable files or archives. These unofficial modifications are made by altering gameplay logic and asset files within a user's game installation, and can drastically change the gameplay experience: from gameplay enhancements and alterations to its mechanics, to replacing the player's character model with a different character model or even something outlandish such as spawning zombies throughout the map. User modification, or modding of games in the open-world sandbox Grand Theft Auto series is a popular trend in the PC gaming community.

While vehicles in the Grand Theft Auto series are loosely based on real-world makes and models, custom vehicle models such as this Audi R8 are a popular form of modification throughout the GTA community.