ImageKit.io - Instant multi-platform image optimization
ImageResizer - Free online app to crop and resize images
Promo Instant Image Resizer - Automatically optimize images for web & social media (free!)
Teeny Tokyo - A surprisingly-powerful bulk image resizing app
Promo.com - Every promotion starts with Promo.com.
Gumlet - Gumlet is an end-to-end video streaming and image delivery platform