To help developers audit Web application security, Google has released an open source tool called ratproxy. It is a non-disruptive tool designed for Web 2.0 and AJAX applications that produces an easy-to-read report of potential exploits.
Ratproxy is a local program designed to sit between your Web browser and the application you want to test. It logs outgoing requests and responses from the application, and can generate its own modified transactions to determine how an application responds to common attacks. The list of low-level tests it runs is extensive, and includes: