I can't believe I just discovered this now. The Tamper Data extension for Firefox.

TamperData is an extension to track and modify http/https requests. It is great for security testing and just in general trying to break your applications. In fact, if breaking is what you want to do, check out the pre-packaged built in SQL Injections, Cross Site Scripting (XXS) vulnerabilities and other goodies.

Here is the options screen.

I've installed it on Firefox 2 no prob, and its pretty straightforward (although these screen captures are from Firefox 1.5). So far the default Code Igniter validation/security is working like a champ, but I've only spent a few minutes playing around.

Here is Tamper Data in action

It also collects data about load time, pages and other useful goodies (including graphing).

I'd love to see some other users with some web-app security experience take it for a test drive.

Thanks Adam Judson for this great Firefox extension.