Frequently people ask me to help them with their web sites, and sometimes they do not even know how their web site was built. Was it made in Joomla? Was it made in WordPress? Is it straight HTML? Is it some fancy CMS? Was it built from scratch? Is it hosted on a Linux platform or a Windows platform? I often need to look carefully through a site to figure out where to point these people, since I only know so many systems (and I do not care to learn them all). What are some ways you can look at the site and determine how the site was built?
Step one: Look at the source code
Browsers display the source code they receive, and just about every browser out there lets you look at that source code. Figure out how to see the source code in your browser. Sometimes it is called "Page Source." I currently use Chrome as my primary browser. To get to the source code I click on the wrench, then go to Tools, and then go to View Source. In Firefox, select the View Source item from the View menu. In the version of Explorer on my computer, View Source is under the Page button.
You will have a much better chance of figuring out how the site was built if the site is small. Larger sites will be more difficult.
Step two: Look for key phrases
Meta tag generator: Search for the meta tag "generator" and see if that shows up. Joomla code shows up with Joomla, version number, Open Source Content Manager. Wiki systems usually have wiki in the tag somewhere. Some versions of WordPress have WordPress and the version number in this field.
Look for "Powered by:" Some web site builders either forget to or choose to not take off the "Powered by" phrase on the site. Search for the phrase Powered by and see if that points you in the right direction.
Look at the URL: Most unix users have web pages that end in .html, whereas Windows users use the shortened .htm.
Look for remnants of an HTML editor: While it does not have anything to do with Dreamweaver, finding this code at the very top of the page has a correlation with websites built in Dreamweaver.
FrontPage likes to leave the word FrontPage in the source code.
You won't always be able to figure out how the site was built, but you can come close.