When cleaning up a heavy mods folder, you may wonder if you still need 
Alexandria Lib after removing other add-ons. Because it only provides shared code for mods built on top of it, keeping it around when nothing relies on it adds no gameplay changes, though removing unused files helps keep your setup easy to manage.
Checking for Dependent Mods
The safest way to find out if another mod in your folder still requires Alexandria Lib is to temporarily move it out and let the mod loader check your setup:
1. Close Minecraft completely.
2. Open your game directory and navigate to the mods folder.
3. Move the Alexandria Lib .jar file onto your desktop instead of deleting it right away.
4.
Reading the Result
If the game reaches the main menu normally, none of your remaining mods rely on Alexandria Lib. You can safely delete the file from your desktop. If the mod loader halts startup and displays a screen stating that another mod requires Alexandria Lib, close the game, move the .jar file back into your mods folder, and relaunch.