"Real browser monitoring is a must." Lenny Rachitsky, TransparentUptime.com

Performance Monitoring

AlertFox makes use of iOpus' iMacros software to automate real browser instances for monitoring internet transactions. The April 2011 update of iMacros allows for creating "Performance Logs" that contain full information about the time each step of the macro took when performing it in a browser.

Of course, we make this information available to our users as well. In case of a transaction sensor failing, you will get a link to the corresponding performance log that allows you to easily see where the macro failed, or where a user experiences slow behavior:
AlertFox Performance Log