In September 2012, Telerik completed the acquisition of the Fiddler Web Debugger , and I announced that I would join Telerik to upgrade my side project to my full-time job. It’s been a busy three years, as we evolved Fiddler from version 2.4.1 to 4.6.2—the changelog alone grew by 1701 entries as we added dozens of major features, hundreds of tweaks, and thousands of fixes. Nearly every line has been touched, and performance and functionality have been improved throughout. We brought Fiddler to Linux , simplified running it in a VM on a Mac and worked to ensure that it remains compatible with all of the latest-version mobile platforms and desktop browsers, including Microsoft Edge. I was able to make long-awaited improvements in areas like Image Analysis , WebSocket inspection , API Testing , extensibility , UI customization , PCAP import and many more. In my off-hours, I even released a Second Edition of my best-selling book “ Debugging with Fiddler .” Perhaps most rewarding of all, I had the opportunity to interact with thousands of customers via issue reports, and speak to thousands more at conferences and webinars. Telerik has honored its commitment to keep Fiddler for Windows available for free, even as we introduced a new fully-supported commercial offering that allows companies to build Fiddler-like functionality into their applications via the FiddlerCore class library .