Font that is used on any websites can be identified using Firebug or Web Inspector. However that can be too complicated for some users. I have posted two Firefox plugins that is able to help you identify the font on a webpage but that restricts you to use Firefox and installing plugins. Here is WhatFont bookmarklet tool, created by Chengyin Liu, an undergraduate Computer Science student at University of Illinois Urbana-Champaign which will probably offer the easiest and cleanest way to help you easily identify fonts on webpages. All you need to do is reveal or show the bookmarks toolbar on your Firefox web browser as it is hidden by default and drag the bookmarklet to the bookmark toolbar to install.
When you are on any webpage and you want to know what font is being used on the text, simply click on the WhatFont bookmarklet that is on the Firefox bookmarks toolbar. After a few seconds, when you see a button showing “Exit WhatFont” at the top right of the browser, it means that you can now start inspecting the font by either moving your mouse cursor to the text which will only show the font being used, or left click on it to show more information such as font family, font size, line height, HTML color code and a sample of the font.
To disable WhatFont, simply click on the Exit WhatFont button which will also automatically close all the popups. WhatFont is free also works on Typekit and Google Font API. Do note that the bookmarklet is only for Firefox. If you want to use WhatFont on Chrome or Safari, it must be installed as extension.