Magickly aims to make image manipulation possible as a simple web service. The Magickly API is very easy to use, and completely open source. It requires no API key, and allows a developer to use a lot of different image manipulations on any web-accessible image. Magickly is an open source, simplified version of the Aviary Effects API, which has a contest ending next week.
Late last year, Google announced a limited preview of its Cloud Vision API beta. After massive participation in the preview, Google has opened its image analysis API beta to the broader developer community. Apps submit images to the platform where a wide array of image attributes are detected.