This SDK is a client library to integrate the ContextualWeb AutoComplete API into your NodeJS applications. The ContextualWeb AutoComplete API provides a way to improve a users search experience by returning a list of suggested queries based on the query string. This API is a RESTful service that provides results to search queries for images with results in JSON. ContextualWeb is a global search engine that crawls web pages from a variety of sources that over the world wide web.
Microsoft is one of the first--and certainly the largest of--customers of Wolfram Alpha's commercial API (our Wolfram|Alpha API profile). For math and nutritional searches, Microsoft's Bing now uses Wolfram results.
SEOmoz, a leader in SEO software, has offered link intelligence APIs for a few years (Mozscape being the latest). Although Mozscape has garnered high adoption rates (over 10 million requests/day), customer feedback uncovered shortcomings. SEOmoz now knows that 10 requests/second and a max of 50 URLs/batch "is not able to support everyone's use case." Accordingly, SEOmoz enhanced Mozscape API capabilities and is currently in beta. Although the beta is in its early stages, throughput has increased 400%.
ResultR deserves mention as it's a meta search engine mashup built by two self-described "Web 2.0 Kids" as a high-school project. With it you can create your own search engine by choosing from 30+ sources you might want to include in your results.