Tick Stasis

Pauses your Minecraft server when no players are online and seamlessly resumes it when a player joins.

While the server is paused:

No updates will occur in the game world, including block updates, entity movement, and random ticks.
In-game time will be paused, which prevents your world's local difficulty from increasing.
Server CPU usage will be reduced to 0% or near-0% (version 1.1.0+).

Commands you enter into the server console will continue to work.

Version compatibility

Tick Stasis is built to be compatible with the following Minecraft versions, including snapshots and April Fools' updates.

Tick Stasis version	Minecraft version
1.1.0	19w11a or later (including 1.14+)
1.0.0	19w04a through 23w51b (including 1.14–1.20.4)

Newer versions of Tick Stasis can be found on Modrinth.

FAQ

Can you update this to a newer version of Minecraft?

Try using the latest version of the mod, even if Modrinth or CurseForge doesn't list the Minecraft version as supported. If you find a version that isn't compatible (due to a crash or other issue), please let me know on the mailing list.

Can you port this to an older version of Minecraft?

This would likely require porting to a different mod loader. See the next question.

Can you port this to Forge/Bukkit/Paper/Spigot?

I might port this to other mod/plugin loaders at some point if I feel like it, but please don't ask about it. In the meantime, the mod is open source and permissively licensed, so you can try porting it yourself.