The Google Shopping Content Java SDK by Google aims to simplify API calls. An example shows hot to interact with Google Calendar, which can be useful to work with the Google Shopping Content API. Authentication Auth 2.0 intends to reduce the amount of code needed. See documentation available at https://github.com/google/google-api-java-client#Documentation
I'm an online shopper who loves efficiency and hates filling out forms, so TwoTap's solution that automates the checkout process across top e-commerce websites immediately grabbed my attention. Not only does TwoTap help automate checkout, but the TwoTap API gives developers a new way to handle referral-based e-commerce. With just a few calls to the API, developers can complete a purchase on a customer's behalf.
While the market seems obsessed with Groupon, other leading deal aggregators are working their way to impressive number of deals offered, subscribers, developer mindshare and big partnerships. Dealmap, the coupon aggregator, has just announced a big partnership deal with Microsoft Bing, where its Dealmap API will be used to publish local and daily deal content to consumers via Bing on the web and mobile Bing offerings.