How can I get web server information about a page I'm viewing (e.g. Apache or IIS, Windows or UNIX)?

When I check pages for broken links using Xenu's Link Sleuth it usefully lists information about the web server, OS and PHP version
e.g.

Apache/2.2.11 (Unix) mod_ssl/2.2.11 OpenSSL/0.9.8j PHP5.2.9

Is there a simple way to extract similar information from the browser when viewing a page e.g. by a Javascript snippet/bookmarklet?

Update
The server information is part of the HTTP response header which is not accessible to Javascript. So a Javascript/bookmarklet solution would not be directly possible (though it could do something like sending the page URL to a site like Arjan's below).

4 Answers

The Web Developer toolbar for Firefox has among its many options a way to view page response headers. (Information | View Response Headers)

curl -I yoursite.com is another simple way to at least see what kind of server it is as well as some other basic header information.

Or from Chrome Dev Tools

Network > All > Headers

Refresh the page then click the site name at the top of the list in the 'Name' panel and look at the Response Headers:
Though for security, fewer and fewer sites include this information nowadays.

The information you mention seems the same as Netcraft's "What's that site running" provides, and they actually have a toolbar (which I've never used). Still note that this information is not by definition The Truth; a web server can report anything it likes.

Also, it's just never as complete^† as the real story.

^{† I didn't know IIS could run on Linux? Ah, Jeff says some parts of SO are Linux, like the load balancer (HAProxy).}