Download & Update Mods
Are you sick of finding and adding that one mod you need? PolyMC is able to download & update individual mods from outside of modpacks using Modrinth and CurseForge.
Minecraft instance management
Did your settings ever reset after launching an older version? Did you ever accidentally break a world because you opened it in an old version? Are you tired of manually switching mods for different versions, installing modloaders?
PolyMC can help. Each Minecraft instance has its own folder, with separate mods, resourcepacks and other things.