WorldEdit is an easy-to-use in-game world editor for Minecraft, supporting both single player and multiplayer, that lets you:
WorldEdit for 1.7.10 is open source and is available under the GNU General Public License v3.
This is a fork based on WorldEdit 6.1.1 for 1.7.10, with the goal of centralizing any improvements and changes into a single location, removing the need for bespoke ASM and mixins from various mods that deeply change world formats, as well as integrating fixes that have been discovered over the years.
Also check out basdxz's 1.7.10 forge fork of WorldEditCUI, specifically built with this version of WorldEdit in mind: https://github.com/basdxz/WorldWide
Some bugfixes and compat patches have been merged in from the gtnh fork