Kindle Cloud Reader, Amazon's HTML5-fueled Web app for reading e-books, is now available on Firefox, the company announced this morning. That brings the total number of compatible browsers for the product to four, if you count Safari separately for iPad and the desktop.
The app was first rolled out for Safari and Chrome in August. It not only makes one's Kindle e-book library more accessible, but allows Amazon to circumvent Apple's controversial in-app purchase fees.
The Kindle Cloud Reader is a natural extension of Amazon's "Buy Once, Read Everywhere" mission. By supporting one of the most popular browsers on the market, the company ensures that even more people have access to the Kindle product from the desktop. In fact, one may have expected to see the app working on the standards-compliant Firefox browser sooner.
Notably absent, of course, is support for the biggest browser of them all, Internet Explorer. Developing any Web-based application for IE can be a headache, and we can imagine something this complex and functional will take some serious time to be ironed out for Microsoft's notorious but widely-used Web browser. If and when IE support does come, it's a safe bet that older versions will be off-limits, as they are less standards-friendly than their more recent brethren.
In addition to launching a fully-functional Web app built on the latest standards, Amazon has embraced HTML5 more broadly by incorporating it into their new Kindle e-book format, which is used in native mobile apps and on the Kindle devices themselves. Kindle Format 8, which supports many of the tags and properties in HTML5 and CSS3, will be used to render e-books on the new Kindle Fire tablet. Other Kindle devices will then be updated to support the new format as well.