Since 2009 onwards Google is working on SPDY protocol pronounced as “speedy” since 2009, an experimental protocol for the faster web and an alternate for HTTP which aims to reduce the latency of pages, Google uses SPDY feature for most of its services like search, Gmail, YouTube etc. and Google added this protocol to Chromium and Chrome browsers. Recently Mozilla joined with Google on this project to avail faster load of pages to its users. Mozilla added SPDY support for Firefox 11 beta which is disabled by default you can enable it through about:config preferences by setting “network.http.spdy.enabled” value to true.
A Green Indicator for SPDY Supported Site in Address bar of Firefox and Chrome After installing SPDY Indicator Extension
In Chrome, you can know the SPDY status of loaded sites by visiting chrome://net-internals/#spdy page in address bar where you can able to see SPDY enabled status for Chrome and live SPDY sessions as well.
It is even much difficult to know which sites serves via SPDY in Firefox, developer Guillermo Rauch created Chrome SPDY Indicator extension which shows green icon in the address bar for loaded SPDY site, other wise shows grey icon for non-SPDY sites.
There aren’t much SPDY enabled sites right now so you most likely to see grey icon in the address bar unless you visit Google, Gmail,Twitter, YouTube and other Google related sites in Chrome, you can disable this grey icon in address bar from the extension options.
You can install this extension from from Chrome web store, here. Inspired from this another developer Cheng Sun created SPDY Indicator for Firefox which you can download from AMO. Remember to enable SPDY support in Firefox 11 beta as said above to test this.
You can try Twitter, YouTube, Gmail, Google.com and other SPDY supported sites you know in Firefox and Chrome browsers after installing this extension.