Web Application Attack Tool can help you automatically find security vulnerabilities in your web applications while you are developing and testing your applications. Its also a great tool for experienced pentesters to use for manual security testing.
These are the key functionalities:

• Intercepting Proxy
• Active and Passive Scanners
• Traditional and AJAX spiders
• Report Generation
• Forced browsing
• Fuzzer
• Dynamic SSL certificates
• Authentication and session support