Amazon has extended the opportunities for distributing web apps and mobile optimized websites by opening up its Mobile App Distribution Portal to HTML5.

This means that developers can now market HTML5 based apps and websites to owners of Kindle Fire and "select Android devices" in nearly 200 countries including US, Canada, UK, Germany, Spain, Italy, France, Brazil and Japan.

The opportunity includes in-app purchasing and selling digital content and subscriptions and Amazon's In-App Purchasing API for JavaScript is provided to help and apps get to use Amazon's virtual currency, Amazon Coins, which being worth one cent each are particularly suitable for small in-app purchases.

Amazon has provided a  Web App Tester that lets you test your web app in a "production-like environment" on your Kindle Fire or Android device. This suite of tools not only helps debug web apps to ensure they work on Kindle Fire and Android devices, it can also be used to create a "native-like experience" by testing apps in the improved web runtime, built on the Chromium browser, available for Kindle Fire HD 7”, Kindle Fire HD 8.9”, and Kindle Fire (2nd generation).

Currently there are very few HTML5 apps for Kindle Fire, so the move should expand the Amazon Appstore catalog - and be another chance to monetize web apps created in HTML5 and websites that are suitable for mobile deployment.

On the other hand this represents another fragmentation of the HTML5 app market. Now you have to create another version of your apparently standard app for a different market place with its own custom APIs.