This is a Minecraft Fabric mod to hide bossbars (e.g. the annoying health bars of Withers and Enderdragons).
The installation of FabricAPI is required. To load the mod you need to run the Fabric mod loader.
Download a jar fitting your Minecraft version from Releases and move the file to your minecraft mod folder ".minecraft/mods/".
Use "/imperm bossbar hide" to hide all bossbars and "/imperm bossbar show" to show bossbars.