App leftover finder for Mac
Type an app’s name. For apps in our library you get every leftover location; for any other app you get read-only Terminal commands that find its bundle ID and list the files it left in your Library.

Uninstall apps and their leftovers in one step
Tidy Mac lists every app with its size and when you last opened it, finds files left by apps you already deleted, and moves an app and its leftovers to the Trash, with Undo in History. $9.99 once, 2 Macs.
How it works
Mac apps name their support files after their bundle ID (for example com.spotify.client) or their own name, inside standard folders in ~/Library: Application Support, Caches, Preferences, Containers, Group Containers and Saved Application State.
For the 16 apps in our uninstall library the exact locations have been checked by hand. For other apps, osascript asks macOS for the bundle ID, and find searches three levels into ~/Library for names containing it, measuring each match with du -sh. A search can match a folder from another app with a similar name, so read each path before removing anything.
Questions
What are app leftovers on a Mac?
Files an app keeps outside its .app bundle: settings in ~/Library/Preferences, data in Application Support or Containers, caches, saved window state and sometimes login helpers. Dragging the app to the Trash leaves them behind.
What is a bundle ID?
A unique name every Mac app has, like com.spotify.client. Most leftover folders and files are named after it, which is why the finder searches for it. osascript -e 'id of app "Name"' prints it, as long as the app is still installed.
The app is already deleted. Can I still find its leftovers?
Yes. The bundle ID command needs the app, but the search by app name still works. If you know the bundle ID (for example from a folder page), type it in the box instead of the name.
Do these commands delete anything?
No. osascript, find and du only read. Look at the list, then move what you want to remove to the Trash in Finder (Go › Go to Folder) so you can put it back if needed.