Mnot's Redbot

Mark Nottingham has put together a really useful tool that aids in the analysis of the behavior of HTTP resources. Visit, type in a web address, and Redbot will report the resource’s cachability based on the returned headers, and provide a helpful list of recommendations for improvement.

Running it on, for instance, flags the fact that I compress the response if the browser tells me that it can accept compressed content, but that I’ve neglected to send the proper Vary header to let caches know that the response needs to be negotiated, and cached based on the Accept-Encoding request header. This is useful, especially for actual applications for which it might matter.

So useful, in fact, that I’m forking it to submit some patches. Mark’s put the Redbot code up on GitHub (mnot/redbot), and I’ve started putting together a command line version based on the web version he’s built.

I’ve mentioned that I love GitHub, right? This is exactly why. :)