Skuuudle - Discover, match and monitor your eCommerce competitors.
userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.
Price2Spy - Price2Spy is a price monitoring, pricing analytics, and repricing tool, meant to help eCommerce professionals keep an eye on their competitors or retailers.
UX Timeline - See how some of today's best companies have evolved
BuiltWith - Find out the technology behind websites
UXReality - UXReality: One App Instead of Lab