Builtwith

BuiltWith is an interesting tool for anyone engaging in CRO, or using tools and apps like these to build out their online business. BuiltWith tracks over 8500 different technologies, recognising their footprints so they can flag up on a search for your competitors’ sites. This means you can find out which tools different websites are using, so you can see whether there are optimisation gains to be made over the competition in using one application or another. Very quick to search, producing detailed, accurate results for any URL.

http://www.builtwith.com