SandBox
SandBox is a worldgen library mod for minecraft forge. It provides an easy way to generate most worldgen json files during datagen and adds some new types of world generation things.
For example, the layered biome source can be used to have multiple biome layers that have their own climate range and don't affect each other. Using a biome layer tag, custom dimensions can be made expandable for other mods.
The extended noise chunk generator allows to replace the surface rules of a noise chunk generator, load surface rules for all biomes that the generator generates and merge them together.