Microsoft finally revealed pricing and more details about how it will sell its Windows Azure cloud-computing infrastructure, making it free for anyone to use now before the company begins charging for it in November.

The pricing narrowly undercuts Amazon on raw computing for Windows-based clouds, but remains more expensive than the Amazon Linux option.

At its Worldwide Partner Conference in New Orleans, Microsoft said it would offer three pricing models for Azure when it starts charging for it later this year. These are: consumption-based pricing, in which people will only pay for what they use; subscription-based pricing; and volume licensing, so enterprise customers can integrate Azure into existing enterprise agreements with Microsoft, said Microsoft General Manager Doug Hauger.

For consumption-based pricing, Microsoft is charging US$0.12 per hour for compute infrastructure; $0.15 per gigabyte for storage; and $0.10 per 10,000 transactions for storage purposes.

For SQL Azure, a cloud database, Microsoft is charging $9.99 for a Web Edition, which comprises up to a 1 gigabyte relational database; and $99.99 for a Business Edition, which holds up to a 10 gigabyte relational database.

For .NET Services - a set of web-based developer tools for building cloud-based applications - Microsoft is charging $0.15 per 100,000 message operations, including Service Bus messages and Access Control tokens.

Bandwidth across all three services will be charged at $0.10 per gigabyte for data coming in and $0.15 per gigabyte for data going out, according to Microsoft. More information about Azure was posted to a Microsoft blog on Tuesday.

Full pricing will kick in when Azure is officially launched as a commercial service at the Microsoft Professional Developer Conference in November. The infrastructure will become available in the UK at that launch, and local-currency pricing will be available at that time.

In March 2010, Microsoft will extend commercial Azure to Brazil, Chile, Colombia, Czech Republic, Greece, Hong Kong, Hungary, Israel, South Korea, Malaysia, Mexico, Poland, Puerto Rico, Romania, Singapore and Taiwan, with other countries to follow thereafter.

During his keynote Tuesday, Bob Muglia, president of the Microsoft Server and Tools division, said their way of differentiating against other providers of cloud-computing infrastructure is its expertise in helping partners and customers build applications. Applications built for the cloud have specific needs to scale out, he said, and Microsoft can help companies figure out how to build them.

"We're building these capabilities into the Windows System Center and Azure platform to enable people to build these scale-out apps," he said. "The cloud is not just an infrastructure play. It's the combination of infrastructure and applications, and Microsoft brings those together."

This need to scale is true for applications running on both public clouds like Azure and Amazon Elastic Compute Cloud as well as for private clouds that companies can build behind their firewall; Microsoft wants to help companies build both, Muglia added.