EngineHub

A Minecraft Map Editor... that runs in-game! With selections, schematics, copy and paste, brushes, and scripting. Use it in creative, or use it temporarily in survival.

WorldEdit CUI is a graphical user interface for WorldEdit, designed to assist in using WorldEdit and prevent accidental errors.

CraftBook lets you create magically extending bridges, compact Redstone circuits, complex Minecart mechanics, and much more... — all without a client mod and fully customizable by the server.