Fiddler (software)

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Fiddler Everywhere.png
Screenshot of Fiddler Everywhere logging HTTP/S network calls
Original author(s)Eric Lawrence[1]
Initial release6 October 2003; 17 years ago (2003-10-06)[2]
Operating systemWindows and later, macOS, and Linux [3]
TypePacket analyzer Edit this at Wikidata

Fiddler is a debugging proxy server tool used to log, inspect, and alter HTTP and HTTPS traffic between a computer and a web server or servers. Fiddler was originally written by Eric Lawrence while a Program Manager on the Internet Explorer development team at Microsoft.[1]

The usage of the name “Fiddler” has broadened to encompass additional products and tools provided by Progress Telerik including Fiddler Classic, Fiddler Everywhere Pro, Fiddler Core, Fiddler Cap, and Fiddler Jam.


Fiddler captures HTTP and HTTPS traffic and logs it for the user to review. The logging is performed by implementing man-in-the-middle interception using self-signed certificates.[4] Fiddler can be used to edit network sessions by setting breakpoints to pause the processing of requests and permitting the alteration of the request and/or response.

The Fiddler Ecosystem offers different products and tools to address specific use cases:

  • Fiddler Classic is the original (and free) debugging proxy tool for Windows only.
  • Fiddler Everywhere Pro is the next generation of Fiddler. Fiddler Everywhere Pro runs on macOS, Windows, and Linux, and has built-in team collaboration and an enhanced UI.
  • Fiddler Core is a .NET library allowing you to capture and modify HTTP and HTTPS traffic.
  • Fiddler Cap is a lightweight Windows-only version of Fiddler designed for non-technical users to capture web traffic and then share the data within the team for debugging.
  • Fiddler Jam (Pilot) is a web-based troubleshooting solution for support teams looking to capture web traffic, web logs and web app screenshots without requiring any programming.


On 6 October 2003, Eric Lawrence released the first official version of Fiddler.[2]

On 12 September 2012, Fiddler was acquired by Telerik and the original author joined the company to work on Fiddler on a full-time basis.[5]

On 22 December 2015, Eric Lawrence announced[6] he was leaving Telerik and the Fiddler project.

On 3 October 2019, Progress Telerik released version 5 of Fiddler.[7]

On 1 June 2020, Progress Telerik released a beta version of Fiddler Everywhere.[8]

On 18 September 2020, Progress Telerik announced the RTW version of Fiddler Everywhere 1.0.[9]

See also[edit]


  1. ^ a b Lawrence, Eric (6 June 2005). "HTTP Performance". IEBlog. MSDN (Microsoft).
  2. ^ a b "Fiddler v1.x Release History". Telerik. Retrieved 7 October 2019.
  3. ^ "Fiddler Web Debugger - Get Fiddler". Retrieved 18 September 2019.
  4. ^ Lawrence, Eric (January 2005). "Fiddler PowerToy - Part 1: HTTP Debugging". MSDN (Microsoft corporation). Retrieved 7 October 2019.
  5. ^ Lawrence, Eric (September 2012). "Fiddler Telerik". Fiddler. Archived from the original on 12 September 2012.
  6. ^ Lawrence, Eric (December 2015). "Fiddler - A Segue". Telerik.
  7. ^ Velikov, Kamen (October 2019). "What's New in Fiddler for Windows v5.0.20194". Telerik.
  8. ^ Velikov, Kamen (June 2020). "Fiddler Everywhere v0.10 is Here!". Telerik.
  9. ^ Pereira, Jonathan (September 2020). "Fiddler Everywhere 1.0 is Here!". Telerik.

Further reading[edit]

  • Lawrence, Eric (16 February 2016). Debugging with Fiddler: The complete reference from the creator of the Fiddler Web Debugger 2nd Edition. ISBN 978-1511572903.

External links[edit]