Gumlet is realtime image resizing and manipulation service. It's aimed to simplify image manipulation, storage on server and delivery for mobile devices.
You just need a free Gumlet account to get started. You can create one here.
Gumlet works by fetching image from the storage you specify, manipulate in realtime and deliver it. All parameters for image manipulation are supplied as query string parameters. The URL can be used anywhere including in IMG tag.
Gumlet is designed to be fast. Our server side processing algorithms use native C++ code and GPUs to get best speed possible for image manipulation. CDN is in-built in our service so no matter where your images are stored, your users will always get the images from closest location possible.