QuickPHP is a PHP Tester and Debugger which is also an extremely lightweight PHP Web Server. It is a PHP Development Web Server - similar to ASP.NET Development Web Server that comes with Visual Studio, except that it's for PHP instead of ASP.NET.

Weighing in at just over 500KB in size and using around 9MB of memory with PHP DLL running, QuickPHP is one of the most lightweight fully functional standalone PHP web server in the world today!

Features:

Freeware
A PHP development web server
The PHP version of Microsoft Visual Studio's ASP.NET Development Server
Extremely lightweight in disk space (file size) and memory footprint
An empty WinForms .NET application uses more memory than this web server!
Ideal for quickly testing your website locally
Without the hassle of converting your machine into a web server
Runs as a standalone application
Serves HTML and PHP files
Tested with PHPBB3 - from installation to a fully running forum
Purely Win32 application - does NOT require .NET framework
No installation required!
Simply unzip into a random folder and run!