The Tictail Go SDK by Evgeniy Vasilev interacts with the API to build applications for online retailers. It includes authentication, tests, and types. Developers' site available at https://tictail.com/developers/
Signifyd, ecommerce fraud prevention service, allows developers to integrate the service with third party ecommerce platforms through the Signifyd API. The Signifyd service uses a number of data points, and allows users to give greater importance to certain points depending on need, to develop a risk score and develop a fraud assessment. From social media activities, to bank data, Signifyd takes a holistic approach to fraud prevention.
Kooaba offers image recognition through its Kooaba API, allowing you to compile metadata on objects in your photos. This can be used for product recognition and pricing, but could also be used to augment personal photo collections, which can be so large that they are nearly impossible to search by hand. There are tons of use cases for image recognition and this API should really open up the field and bring more applications to market.