Have you ever wondered what CMS a particular site was using? Or what stack a site was developed on?
Wappalyzer is a browser extension that shows you what software is used by a site. The plugin is available for both Chrome and Firefox, and works as intended.
The website http://www.wappalyzer.com also shows you stats from the past 90 days of the most popular software used on the web.
Some interesting tidbits, WordPress accounts for 56% of CMS usage on the web, with Joomla next at 19% and Drupal at 9%.
Wappalyzer also has an interesting business model. While they provide developers a very useful tool, they are also collecting the data and selling them as datasets.
All in all, I would highly recommend this browser extension be a part of any web users tools.