FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Flickr - image and video hosting website
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
PhotoPrism.app - PhotoPrism® is an AI-Powered Photos App for the Decentralized Web. It makes use of the latest technologies to tag and find pictures automatically without getting in your way. You can run it at home, on a private server, or in the cloud.