Flickr - image and video hosting website
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
ImageShack - Unlimited space to host images, easy to use image uploader, albums, photo hosting, sharing, dynamic image resizing on web and mobile.
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.
Dropbox - Online Sync and File Sharing
Photobucket - Photobucket offers image hosting and free photo and video sharing.