WhatRuns is a free browser extension that will automatically recognize and add the technology stack of the website you visit. WhatRuns is a one-click away for you to find out what runs a website. 

WhatRuns is an effort to help people find the technology used on a website. It is also a part of the new wave of the technology web where it's getting harder to figure out what runs a website. The tool can detect a huge amount of tech stack including server-side frameworks, web technologies, databases, CMSs (and their plugins), and fonts to name a few categories.

Once you install it, you can start to see what technology runs a website.