fdupes - FDUPES is a program for identifying or deleting duplicate files residing within specified...
Flickr - image and video hosting website
Rdfind - Rdfind is a program that finds duplicate files.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Google Photos - All your photos are backed up safely, organized and labeled automatically, so you can find them fast, and share them how you like.