Clearbit - Clearbit provides Business Intelligence APIs
Skuuudle - Discover, match and monitor your eCommerce competitors.
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
Price2Spy - Price2Spy is a price monitoring, pricing analytics, and repricing tool, meant to help eCommerce professionals keep an eye on their competitors or retailers.
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.
BuiltWith - Find out the technology behind websites