Burp Suite is an integrated platform that was built to attack (pentest) web applications. The platform contains dozens of hacking tools with numerous GUI interfaces that facilitate and speed up the process of attacking an application. As ever, the tool is designed to think like a black hat hacker would.
All of the tools within Burp Suite share the same framework for handling and displaying HTTP messages, persistence, authentication, proxies, logging, alerting and extensibility. The free version is limited but will give you an excellent indication and feel of how to attack (pentest) a web application.
Burp Suite Tutorial
