Disclaimer: I'm not responsible for any farms decimated, irreplaceable items voided or worlds otherwise destroyed from the use of this mod. Use with care. :)

StreetSweeper sets a configurable cap on entities in the world. When a world is loaded or saved, or when it is triggered through the '/streetsweeper' command, Sweeper will check the number of loaded entities is not exceeding the cap. If it is exceeding the cap, it will remove entities in order of age, oldest first, until the cap is no longer exceeded.

The provided config allows you to adjust the cap, disable automatic firing of the sweeper, and also filter what kinds of entities are destroyed. The defaults are setup to cause as little damage as possible, avoiding deleting bosses, anything the game considers invulnerable (such as Tinker's Tools!) and anything named. What it will purge by default are mobs (both passive and hostile) and items.

As of version 3.0.0, StreetSweeper uses the EntityType tag streetsweeper:sweepables to determine what can be swept. It defaults to items and experience orbs only. The config spec was changed and now allows for some things to be set to never removed, such as tamed animals.

Yes, you could do everything this mod does with a /kill command. But having a mod that you can just set and forget instead seemed like it would be useful. (Besides, I was almost done programming the mod by the time I remembered the kill command had good targeting now) So here it is.

It is highly configurable, and if you want more options, just ask.