Ranked in these QuestionsQuestion Ranking
Pro Handles fast CDN transformations for you
Uploadcare doesn't require you to define cached transformations, and handles them quickly for you so you don't have to fiddle with configurations.
Pro Open source API
Their APIs are open source on github so you can see the source and provide pull requests.
Pro Clean and thoughtful client side API.
Uploadcare provides a client side widget and API, with well worded documentation that clearly explains how each part of the widget is implemented. The client side API also implements the jQuery promises interface for cleanly defining callbacks and updating with progress.
With the client side API decoupled from the upload interface, you can much more easily create customized UI's that match the look and feel of your site.