Script Minecraft from inside the game. Write code that reacts to what's happening (chat, blocks, entities, GUIs, world events, every tick), bind it to a key, draw overlays on the HUD or out in the 3D world, and automate the parts you'd rather not do by hand. Everything runs client-side, so it works on any server you can join.
Scripts can be JavaScript, Python, or Ruby. The whole API is documented, and the devkit ships TypeScript definitions so your editor autocompletes against the real game objects instead of making you guess.
Versions
This is the community-maintained continuation of JsMacros, built for current Minecraft: 26.1+, Fabric, Java 25. It does not support 1.16 through 1.21. Starting in 26.1 Mojang ships Minecraft deobfuscated, which let the code drop its mapping layer but also moved it far enough from the older versions that keeping them in one codebase stopped being worth it. For those, grab an older JsMacros build.
Extensions
Python and Ruby ship as separate extension jars. Drop the one you want into config/jsMacros/extensions/, or use the bundle that puts them there for you.
Source and issues: https://github.com/grepsedawk/JSMacros
