The requirements for ProofBuddy shouldn’t be too much of a stretch for most web servers.
The most likely restriction you will come across is a server with safe_mode enabled.
ImageMagick - My test servers are running versions 6.2.2 and 6.2.8. This is used to scale uploaded images and to create thumbnails as well as create the black & white and sepia images when they are requested.
Sepia toning is known not to work in version 6.0.7
GD Library - If your server does not have ImageMagick you can also use the GD library that most servers have installed.
PHP - I have tested ProofBuddy in PHP versions 4.3.4, 4.4.2, and 5.1.4. Safe mode must be off.
MySQL - Tested in versions 4.0.18, 4.1.18, and 5.0.21.
Apache - ProofBuddy should work with other web servers, but it hasn’t been fully tested. Currently it has been tested under Apache 1.3.34, 2.0.48, and 2.0.55.
JavaScript - The administrative side requires JavaScript to be enabled. JavaScript is not required for your clients if you are using one of the default themes, although other themes may require JavaScript support.