Where Does PolyMC Store Instances?
PolyMC keeps instances, mods, and worlds under its data folder (~/.local/share/PolyMC on Linux), with a Flatpak variant and Prism as the maintained successor.
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PolyMC organizes everything by instance: each modded setup gets a folder with its own .minecraft, saves, mods, and Java settings. The parent data folder sits in the usual per-OS location, with worlds nested inside each instance rather than in a shared Minecraft folder.
One honest caveat: PolyMC development ended and the project continued as Prism Launcher. The Linux paths below are documented from the project itself; the Windows and macOS spots follow the same Qt conventions Prism uses. Back up the whole data folder before migrating launchers.
Where PolyMC stores this, by platform
~/.local/share/PolyMC/instances
Instances, assets, and libraries all nest under here. Each instance folder carries its own .minecraft/saves. Add portable.txt in the PolyMC root to switch an install to portable mode.
~/.var/app/org.polymc.PolyMC/data/PolyMC/instances
Flatpak sandbox path. The inner PolyMC folder mirrors the native layout, which is why Prism's migration guide has you copy it across and rename it.
%APPDATA%\PolyMC\instances
Follows the same Qt data-location convention as its Prism successor. If your install used a custom or portable path, check beside the executable first.
~/Library/Application Support/PolyMC/instances
Same convention-derived spot as Windows. Prefer migrating to Prism Launcher over setting up PolyMC fresh; Prism documents the same layout and stays updated.
Frequently asked questions
PolyMC is discontinued. What should I use instead?
Move to Prism Launcher, which is the maintained fork of this codebase. Prism reads a migrated copy of the PolyMC folder: copy it into Prism's data directory and rename it to PrismLauncher.
Where are my PolyMC worlds?
Inside instances/[Name]/.minecraft/saves, one folder per world. Copy the world folder into another instance's saves directory to reuse it under a different mod set.
Notice an outdated path? Let us know.