How do I detect what browser is used to access my site?

Question

How do I detect what browser (IE, Firefox, Opera) the user is accessing my site with? Examples in Javascript, PHP, ASP, Python, JSP, and any others you can think of would be helpful. Is there a language agnostic way to get this information?

Answer 1

If it's for handling the request, look at the User-Agent header on the incoming request.

UPDATE: If it's for reporting, configure your web server to log the User-Agent in the access logs, then run a log analysis tool, e.g., AWStats.

UPDATE 2: FYI, it's usually (not always, usually) a bad idea to change the way you're handling a request based on the User-Agent.

Answer 2

Comprehensive list of User Agent Strings from various Browsers

The list is really large :)