There are 2 repositories under age-of-empires-iv topic.
C# library and tools for working with Age of Empire 4's Essence engine (.sga, .rrtex, .rrgeom, .rgd currently)
Source code for aoe4guides.com: Yet another Age of Empires IV build order tool
Template for getting started with Age of Empires 4 TypeScript modding
Awesome wikis and tools for Age of Empires IV ;)
A command line tool for selecting a random civilization in the game Age of Empires IV.