Windows
C:\Program Files (x86)\Steam\steamapps\common\Portal 2\portal2\save
macOS
~/Library/Application Support/Steam/steamapps/common/Portal 2/portal2/save
Linux
~/.steam/steam/steamapps/common/Portal 2/portal2/save
Windows
C:\Program Files (x86)\Steam\steamapps\common\Portal 2\portal2\save
macOS
~/Library/Application Support/Steam/steamapps/common/Portal 2/portal2/save
Linux
~/.steam/steam/steamapps/common/Portal 2/portal2/save