When developing web pages for mass consumption, one of the most important things you can do with your content is to make sure it is being transmitted in a compressed manner. Typically for web pages, the way to achieve this is to gzip your content. If your browser supports this, it will report its support to the browser as one of the headers when it requests a page. When the web server receives this, if it has the correct setup it will render the content, place it into memory, run a compression algorithm on it, and transmit it. On the client side your browser will then take the compressed stream, uncompress it, and render the page to the user. This may seem like a lot of steps, but in actuality, the slowest part of the request/transmit/rendering process for web pages is usually the internet transaction, and compression can speed things up many times.
When setting up this type of compression, or when testing the setup of an existing server, it can be very helpful to have a tool that will report whether a given URL is being sent gzipped or not. In order to address that, I have built a GZIP Detector. Simply give it a URL, and it will tell you whether or not that URL is being transmitted in a compressed format. There are many other ways to detect this, but they aren't always handy, or they require specific software or browsers.
Hopefully this GZIP Detector will provide value to someone besides me.