My friend and coworker Curt Barnard recently introduced me to what quickly became my new favorite browser plugin- Wappalyzer.
Wappalyzer is a web browser plugin that passively identifies many of the technologies a web page is using, sometimes with an eerie degree of accuracy.
As you can see in the figure above, Wappalyzer not only correctly identified that my web server was running Nginx and Ghost written in Node.js, but also that my site uses CloudFlare CDN and Google Analytics.
The plugin is open source, takes up very little space in the browser, is great for situational awareness, and makes it a snap to identify web technologies quickly (which is useful if you are a security consultant/penetration tester).
Quick disclaimer- the plugin does ask to send web statistics back home, but you can opt out on installation.