DimWorldBorder

As of Minecraft 1.21.9, the DimWorldBorder mod is obsolete, as the functionality for independently configuring world borders for each dimension will be added to the base game!

DimWorldBorder is a mod for Minecraft 1.21 on NeoForge/Fabric, enabling server administrators to customize world borders independently for each dimension (Overworld, Nether, End, and others).

Server-side only; no client installation required.

Command System
The /dimworldborder (or /dwb) command allows:
Set border size: /dimworldborder <dimension> set <size> [time]
Expand/shrink border: /dimworldborder <dimension> add <distance> [time]
Set border center: /dimworldborder <dimension> center <x> <z>
Adjust damage: /dimworldborder <dimension> damage amount <value> or /dimworldborder <dimension> damage buffer <value>
Configure warnings: /dimworldborder <dimension> warning distance <blocks> or /dimworldborder <dimension> warning time <seconds>
View border size: /dimworldborder <dimension> get

Getting Started
Install the mod on a NeoForge/Fabric server (Minecraft 1.21)
For details, type /dimworldborder in-game
Configure borders for each dimension