Most modern digital versions (like Steam or Rockstar Launcher) use the 1.1 executable, which is with many popular mods and scripts.

The CLEO Library allows you to add custom scripts (like new missions or cheat menus) without modifying the main game files.

ModLoader is the most important tool for modern modding. It allows you to install mods by simply dropping them into a folder, keeping your original game files untouched.