DarkCap
Experience Limitation in Minecraft
The DarkCap modification sets a maximum limit for accumulated experience (XP) in the game at 1000 units. This is a simple yet effective solution for situations where players gain too much experience.

Main Features
The mod constantly monitors the player's experience amount and automatically returns it to the value of 1000 if it exceeds this limit. This is particularly useful for servers and modpacks that contain various modifications allowing rapid accumulation of huge amounts of experience - thousands or even millions of units.

Compatibility Features
DarkCap fully supports server-side installation - you can install it only on the server, and clients won't need to install the mod on their computers. This makes it an ideal solution for multiplayer servers.
Developers allow using DarkCap in custom modpacks without restrictions.
The authors of this modification also created the popular DarkRPG modpack, which offers full RPG gameplay with quests and expanded features.