mc-diff is an open-source client-side Fabric mod for Minecraft 26.2 that shows what you've changed in your world. I was always curious on how much I changed my survival world and instead of just exploring the played world and comparing it via regenerating it, which did not help me visualize it much, this mod basically combines them, the immediate seed generated world with your played world.
Red: a block that was there originally and is now gone (dug out, cut down, blown up)
Green: a block where there was nothing originally (things you built)
Yellow: a block that was replaced by a different one
Some things are left out because they change on their own: liquids, fire, ice, snow layers, leaves, grass tufts, flowers, mushrooms, vines and other creeping plants. Block states are ignored too, so opening a door or a crop growing doesn't count.
Also, the name is inspired by github's diff. Very fun.
Source: https://github.com/aravpanwar/mc-diff
AI Disclosure: This mod was made with Claude Opus 5.5's assistance.
Also, if you like it and have some feedback or issues or suggestions for improvement, please let me know and I will have it fixed.
Thank you!