The Anniversary Edition makes use of two core tools when installing mods. "Core" means that they are installed automatically, as opposed to some additional tools that can optionally be installed from the Tools menu in the AE Installer.
- OniSplit - Used for breaking the game's level data files into individual resources, then for making new data files from the original resources after they are combined with the resources in the user's selected mods. Runs in the .NET environment (provided by Mono on Macs).
- XmlTools - Used for applying XML patches from mods to resources before OniSplit creates new data files from them.