Steam keeps shader caches and downloads long after the game is gone
Games are the obvious part. The workshop content, shader caches and interrupted downloads around them are what nobody uninstalls.
Games are honest about their size, which makes Steam an easy folder to deal with. What is less obvious is that uninstalling a game leaves several things behind, and that the library folder holds more than the games themselves.
Where it all lives
du -sh ~/Library/Application\ Support/Steam/* 2>/dev/null | sort -h | tail -10
du -sh ~/Library/Application\ Support/Steam/steamapps/common/* \
2>/dev/null | sort -h | tail -15steamapps/common is the games. The folders beside it are the interesting part:
| Folder | What it is | After uninstalling a game |
|---|---|---|
steamapps/common | Installed games | Removed |
steamapps/downloading | Partial and interrupted downloads | Often left behind |
steamapps/shadercache | Compiled shaders per game | Often left behind |
steamapps/workshop | Mods and workshop content | Left behind |
userdata | Saves and settings, per account | Left behind, and you want it |
The three folders to check after a clear out
du -sh ~/Library/Application\ Support/Steam/steamapps/downloading \
~/Library/Application\ Support/Steam/steamapps/shadercache \
~/Library/Application\ Support/Steam/steamapps/workshop 2>/dev/nullShader caches and interrupted downloads are pure debris once the game is gone, and workshop content can be several gigabytes for a game you stopped playing two years ago. All three are safe to remove; the game reinstalls what it needs.
What not to delete
userdata holds local saves and settings for games that do not use cloud saves. It is small and it is the one folder here that cannot be recreated. Leave it alone unless you have checked that everything you play syncs saves to the cloud.
Uninstalling properly
Use Steam's own uninstall rather than deleting a folder from common, because Steam otherwise still believes the game is installed and shows it as broken. From the library, right click the game, Manage, Uninstall.
Once the library is dealt with, the same question applies to everything else on the Mac: a game folder is a large obvious thing, and the folders that are not obvious are usually where the rest of a full disk is.
Common questions
Where does Steam install games on a Mac?
In ~/Library/Application Support/Steam/steamapps/common, one folder per game, with shader caches, workshop content and partial downloads in sibling folders. Saves and settings are kept separately under userdata.
Does uninstalling a Steam game remove everything?
No. The game folder goes, but shader caches, workshop content and interrupted downloads are frequently left behind, along with the save data under userdata, which you usually want to keep.
Is it safe to delete the Steam shader cache?
Yes. Shaders are recompiled the next time you play, which costs a little loading time on the first run. For games you have uninstalled the cache is pure waste.
Can I delete a game folder directly instead of uninstalling?
You can, but Steam will still list the game as installed and show it as broken until you verify or uninstall it properly. Using Manage, Uninstall from the library avoids that.