FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Flickr - image and video hosting website
digiKam - Professional Photo Management with the Power of Open Source
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Adobe Photoshop Lightroom CC - Adobe Photoshop Lightroom CC is a commercial photo processor and image organizer.
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.