Html – How to determine what technology a website is built on?

frameworkshtmlreverse-engineering

Quite often I come across a nice looking or functional website, and wonder what technology was used to create it. What techniques are available to figure out what a
particular website was built with?

Few frameworks seem to include any kind of generator meta tag like web editors do. Are there any tell-tale signs of particular languages and/or frameworks?


Summary of answers

Site URLs may betray the framework and/or programming language but cannot be relied upon (e.g. file extensions such as .asp). HTTP response headers, cookies, stylesheets and source comments may also give clues.

Some nice tools for querying site details (no doubt there are many more):

Firefox addons:

Chrome Extensions:

Bookmarklets:

Best Solution

You could use http://builtwith.com to figure out which server and programming language was used. For example it told me that SO uses IIS7, google analytics, html4 and utf8.

If you want to know the framework...well that will probably not be possible just from looking at the site. Why don't you write them an email? ;)