Sometime, when you found a site looked amazing and functional, you want to know what technology / platform / CMS that was used for building that site. The following is a list of tools that can help you check what kind of components that the site operates with.
But you may also wonder how these online CMS / platform detection work. I think by checking the site urls, and file extensions, HTTP response headers, source code for comments, or standard JS libraries, it could give some clues, as CMS using combinations of components can leave some unique libs and patterns, exactly as "signatures" of a particular platform.