Flickr - image and video hosting website
TexturePacker - Texture Packer is hands down the best sprite sheet generation tool on the market.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Free Texture Packer - Free Texture Packer is an open source tool that allows you to pack multiple images into one atlas for you games or sites.
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.
Sprite Sheet Packer - Sprite Sheet Packer is online that you can easily use to pack sprite sheets, including data formats for CSS, LESS, and Phaser.