The free tool, called DOM Snitch, is designed to sniff out potential security holes in Web applications' client-side code that could be exploited by attacks such as client-side scripting, Google said on Tuesday.
In addition to developers, DOM Snitch is also aimed at code testers and security researchers, the company said.
The tool displays DOM (document object model) modifications in real time so developers don't have to pause the application to run a debugging tool, according to Google.
DOM Snitch also lets developers export reports so they can be shared with others involved in developing and refining the application, Google said.
Google is working on DOM Snitch and on server-side code testing tools such as Skipfish and Ratproxy because it believes that the number of security holes in Web applications is growing along with their overall sophistication and complexity.