HTTP Header Spy is a free Chrome add-on developed by Michiel Roos. It falls under the category of Browsers and specifically the subcategory of Add-ons & Tools. With this tool, users can easily inspect request-response headers and cookies right after page load, eliminating the need for extra clicks.

One of the main features of HTTP Header Spy is the ability to view headers and response times without opening the page inspector tool. Users can conveniently access this information directly on the page they are viewing. The add-on also offers an auto-hide feature for information panels, allowing users to specify the time after which the panels will be automatically hidden.

Additionally, HTTP Header Spy provides various features to enhance the inspection process. Users can view server IP, XHR and sub-frame requests, and follow the full redirect path. The add-on also supports showing HSTS requests and offers colorful status indication icons for easy identification.

Users have the option to inspect form data, get parameters, and cookies, making it a comprehensive tool for analyzing HTTP headers. The add-on offers a micro mode that displays only the chosen response headers, allowing users to focus on specific information.

HTTP Header Spy provides customization options as well. Users can position the add-on in one of the four corners of the window and choose between a light and dark color scheme. The add-on also allows users to filter headers to be shown and highlight any string pattern in the header views.

In conclusion, HTTP Header Spy is a valuable Chrome add-on for inspecting request-response headers and cookies. Its user-friendly interface and range of features make it a useful tool for developers and web professionals.