The primary resources for modding HITMAN 3 are the Simple Mod Framework, ZHMModSDK and Peacock.
Automatic mod file conversion, tools for keeping mods compatible and updated and much more.
A (still fairly experimental) modding SDK and mod loader that allows mod DLLs to dynamically alter the game with C++.
A server replacement that allows for adding contracts, items and more, integrated with SMF.
If you want to develop mods yourself, there are quite a few tools available:
Allows for reading and writing the game's RPKG files as well as converting many of the game's formats to and from more readable ones.
A complete solution for editing the game's entities (TEMP and TBLU files). Source (on GitHub) is licensed GPLv3.I didn't design a logo so it's just the default Tauri one.
A few tools, including the main ResourceTool which converts between JSON and a wide variety of BIN1 game formats.
A few tools, including the main HMTextureTools which let you convert the TEXT and TEXD files to TGA.
A Blender addon for viewing and editing game assets (meshes, bone data, physics and animations).
A tool for exporting Wwise projects into the WWEM/WWEV/etc. formats of the game.