Flickr - image and video hosting website
Syncany - Syncany is an open-source cloud storage and filesharing application.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Filestash - Filestash is a modern client for FTP, SFTP, S3, WebDAV, Minio,...
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