Among the vulnerabilities RatProxy is able to test for are cross-site scripting flaws and incomplete cross-site defense mechanisms, as well as potential data leak sources and risky code that retrieves data from outside domains.
The company hopes that developers will put the tool to use when coding new web-based services that rely on multiple sites and outside sources for data.
Google security engineer Michal Zalewski warned, however, that the tool should not be considered a substitute for a thorough analysis by a security professional.
"We feel it will be a valuable contribution to the information security community, helping advance the community's understanding of security challenges associated with contemporary web technologies," Zalewski said. "We believe that responsible security research brings a net overall benefit to the safety of the web as a whole, and have released this tool explicitly to support that kind of research."
Users can download the tool from the Google Code site. The tool works on Windows, Linux, FreeBSD and Mac OS X operating systems.