WhatRuns is a free browser extension that shows you what runs a website – from ad networks and developer tools to fonts and Wordpress plugins. You can also follow websites and get notified when they add or remove technologies.
We soft-launched a couple of weeks back and was lucky enough to be picked up by the Chrome team. We were featured on the Chrome Webstore, landing us 12k active users in one week. It was a huge validation and helped us tremendously in squashing bugs and making a finished product. We realise we have a long way to go, and our little team is working round the clock to make it happen. 🚀
Hope you find this useful, and would love to hear what you think :)