Ajax View: Remotely Monitoring Web 2.0 Applications
The goal of the Ajax View project is to improve developer's visibility into and control over their web applications' behaviors on end-user's desktops.
The Ajax View approach is to insert a server-side proxy (or web server plugin) in-between the web server machines and the end-user's browser. This proxy captures the web application's JavaScript code as it is being sent to a browser and rewrites the code to insert extra instrumentation code. The injected instrumentation code runs with the rest of the web application inside the end-user's browser and can capture performance, call graph, application state and user interaction information, providing visibility directly into the last hop of the user's experience.
Check this out : http://research.microsoft.com/projects/ajaxview/
You can download it here.
Note:
As an alternative, you can use Fiddler (http://www.fiddler-tool.com) or Web Development Helper (http://projects.nikhilk.net/Projects/WebDevHelper.aspx) or Burp Proxy (http://www.portswigger.net/proxy ).