Flickr - image and video hosting website
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
BuildFire - BuildFire is the easiest way for small businesses to build a mobile app in a matter of minutes for iOS and Android.
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.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.