GAPS is an image sorting and viewing application written to deal with enormous folders full of images. It can easily handle hundreds of thousands of images per folder and continue to operate quickly and stably.
GAPS' DuperFinder feature can scan all of your image folders for duplicates, shows you thumbnails of the dupes as confirmation, and easily removes the extra copies to save disk space.
With GAPS' image sorting features, you use your keyboard to quickly sort images from an "Incoming" folder into multiple folders of your choosing. You can sort images one at a time or in batches by using your mouse to select