Dragging a Mac app to the Trash leaves behind preferences, application support folders, login items, and launch agents that nobody bothers to remove. AppCleaner finds the lot — drop an app onto its window and it lists every related file across ~/Library and the system, ticked and ready to delete. Its SmartDelete mode also watches for apps you’ve already trashed and offers to clean up the leftovers. Free, lean, has been a “first day on a new Mac” install for a decade.