Microsoft is giving testers the first chance to get their hands on the browser-based versions of its Office applications. Access to the early preview is by invitation only, but the software giant has promised a public beta later in 2009.

The Office Web Applications - versions of Word, Excel, PowerPoint and OneNote - officially form part of Microsoft's Office 2010 suite, but were not made available with the Technical Preview of the suite when it was released to testers in July.

Microsoft's Office Client product manager, Chris Adams, said that today's release is "an early first look, and by no means feature complete", and added that it would be the first time users get to see the web versions of the applications.

Adams revealed that the Office Web Applications are still a work in progress, and that testers will have access only to Word, Excel and PowerPoint to start with. Only Excel and PowerPoint currently offer the ability to create and edit files, and only Excel currently has support for multi-authoring, whereby two or more users can work on the same document simultaneously.

The Office Web Applications support basic editing, such as text changes, formula edits and formatting changes.

However, the applications are cross-platform, running in Internet Explorer, Firefox or Safari, and content appears exactly like it does in the client-based versions, according to Adams.

In a live online demonstration, Microsoft showed how the same Excel spreadsheet can be opened in two browsers. Changes made to one propagated through to the other after a second or two. The company also showed how a presentation could be edited then run as a slide show using the web version of PowerPoint.

Adams reiterated that the Office Web Applications will be available for free to consumers signed up for Microsoft's Windows Live online services.

Subscription access to the applications for businesses will be available through SharePoint Online, part of Microsoft's Business Productivity Online Suite, while enterprises will be able to run the applications on-premise via SharePoint server.

There will be some differences between these versions. Consumers can save documents to Windows Live SkyDrive online storage, and publish to third-party wikis and blogs, and access will be advertising-supported, according to Microsoft.

Businesses will be able to save documents to SharePoint stores, network shares and local drives, and will have access to administration tools and document lifecycle features.