How to Install a PoE 2 Loot Filter
After exporting a filter, the game needs the .filter file in its item-filter folder. These steps describe the Windows path shown in LootBase.
Save the file
In LootBase, choose a file name ending in .filter and use Save as. On Windows, the usual folder is %USERPROFILE%\Documents\My Games\Path of Exile 2.
If your Documents folder is redirected or you use another platform, use the folder control in the game settings to locate the correct directory. Keep custom sound files alongside the filter when your rules reference them.
Select it in Path of Exile 2
Open Options → Game → Item Filter, select the saved filter and apply the change. If it does not appear, check that the file is in the correct folder and has a .filter extension rather than .filter.txt.
After editing the filter in LootBase, save the updated version and reload or reselect the filter in game so the new rules take effect.
Keep your own copy
LootBase settings are editable in the browser, but the exported .filter file is the version the game reads. Keep a copy of a working filter before making larger changes.