Website Development - Determining Program Language

I know the basics for html, however, when it comes to programming a website I typically purchase themes (wordpress and joomla) and modify them as needed.

Is there any website that allows somebody to punch in a domain and get back what it was written in?

I have seen websites with the PHP extension and have been unable to figure out if it was a custom made job or template. Most times it's Wordpress or Joomla, but I've seen some great designs and wonder where the owner got them from.

Does anybody know a step by step process to figure out if it's a custom job vs. template that is different then following.

Thanks

Looking at the source code helps. Most templates will be named and you will find them in certain folder for the CMS to work.

Google prefers html pages over server side scripting languages (php,asp,cfm etc..) A lot of website developers use scripting to hide the extension or show an html page when it is actually a PHP page. So click around until you find a page that is not ".html". For example add to cart or login. Find a page and click view source. Look for a folder reference in the code i.e. wp-content/images/blah.jpg. Folder structure will give you an indication as to the script.