IAmREGE

A client-side mod allows you use custom directories for reading and saving singleplayer worlds.

Enable you to override the target main class's Java Program arguments with arbitrary arguments using Mixin (by SpongePowered). And without changing cmdlines(in Task Manager or Htop)!

A plugin run on server-side, which allows you to refuse some crafting operations from client-side.

Add a “Search World” box for MC pre-1.13 || Enhance the searching behaviour

Command /schedule, but with realtime, and no need to worry about the TPS!