AppFog is aPortland, Ore.based company which started out as a PHP-specific PaaS called PHPFog. Last year, it added support for Java, .NET, and Node and other popular languages and decided to restructure its foundation atop standard Cloud Foundry technology. That means AppFog can run across the major public clouds, including Amazon, Rackspace, Microsoft and HP.

Now, AppFog is making cloud computing a lot easier for companies. AppFog’s platform as a service now abstracts out the tweaking and tuning of cloud servers, databases and storage. And it lets you switch clouds easily, giving you the ability to choose your cloud with the click of a button.

AppFog CEO Lucas Carlson explains: “We become your front-end to cloud. We took a standard Cloud Foundry API and delivered that across all the public clouds.” The resulting PaaS has been put through its paces by 5,000 beta testers including the City of New York and 40,000 developers.

One of the beta testers is Matthew Knight, founder and CEO of Merchpin, and he is impressed with the service. “We were building our application and also having to deal with maintaining our servers. It was a pain. AppFog fixes that,” he said. That and its tight integration with MongoDB, Merchpin’s database of choice, make implementation and deployment extremely easy.

AppFog will cost more than Amazon alone but Knight says when you factor in man hours, it’s much less expensive.

Companies can set up a free AppFog account with 2 GB of RAM. There are options for additional RAM, including 4GB for $100, 16GB for $380 and 32 GB for $720. AppFog will bill the customer for the entire infrastructure stack, including the backend cloud, giving it pretty good account control.