Mob Switch

This mod creates a UI menu, as seen above, that either allows, or disallows, the spawn of hostile mobs in your world. This mod does NOT affect any hostile mobs with nametags, so all of your farms will remain intact! When toggled on, all loaded mobs that have already spawned will immediately despawn, and no other hostile mobs will be allowed to spawn.

Before and After toggling Mob Spawning. This mod is very straight-forward. Either lots of mobs or no mobs.