Resizing.app - Image resizing has never been so simple with free online resizing.app. Convert, optimize, resize images with ease and for absolutely free.
ImageKit.io - Instant multi-platform image optimization
Gumlet - Gumlet is an end-to-end video streaming and image delivery platform
Piio - Generates responsive images so you don't have to optimize
imgix Sandbox - Resize & process images in real-time w/ simple URL commands
Pixelhunter.io - Free AI image resizing tool for social media