Spawn Controller

The mod lets a server owner set a cap on how many entities of a given identifier can be present in the world at one time. Once the cap is reached, no further entities of that type spawn until the count drops. A separate cooldown setting controls the delay before the next spawn of the same type, and both values are entered in ticks.

Ticks are the unit the game uses internally, with 20 ticks to one second, so a delay of 5 seconds becomes 100 ticks. The example given in the author notes limits the vanilla cow to a spawn only every 1000 ticks. Each entity type is added as a separate entry, using its identifier such as minecraft:cow, with a cap and a cooldown. Changes are applied with the Apply Changes button in the configuration screen and are saved from there.

Spawn Controller is built on Fzzy Config, which the author notes list as a dependency. It is published for NeoForge 1.21.1 only. Only the server has to run it, while players can install it or leave it out. The code is not open source; it is released as All rights reserved.