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Clearbit provides a collection of APIs designed to help businesses grow by turning partial information into full contact data, looking up company data by domain name, helping with OFAC compliance and screening, and providing address auto-complete and verification.

Introspectr is a personal search engine that indexes a users Facebook, Gmail, and Twitter accounts as well as the content from any email attachments or underlying pages from any links. Users can search any term and find all of the tweets, emails, or facebook notifications associated with that search query.

A PeekYou profile aims to help other people find their websites, social-networking pages, photos or anything else about users online. You can also create a profile for friends or relatives to ensure that they may also be easily found online. You can also register to become a full Contributor which aims to allow users to track their edits to PeekYou and aims to give users other benefits as well.

Pipler is a candidate search engine that transforms the web into a talent pool. It extracts, synthesizes and structures public information from all over the Internet into easy to read profiles.

Ark is a people search engine based on filters that crawls major social networks, including Twitter, Facebook, RenRen, LinkedIn. The company indexes profiles across social networks, providing a unified social graph.

Qwerly is a company that offers a data API to develop sales leads for the social web.