Microsoft is giving away free software to early-stage Web start-up companies as part of a worldwide program called BizSpark launched on Wednesday.

BizSpark aims to help startups get off the ground by providing production licenses and technical support for several Microsoft products. The licenses are free for the first three years, after which the startups must start to pay.

As well as helping startups, the program gives Microsoft a way to promote the use of its software at a time when open-source alternatives have matured, and as rivals such as Google and Salesforce.com are promoting their cloud platforms for building Web applications.

ZocDoc, a New York-based company that offers an online service for booking doctor and dentist appointments, became an early pilot member of the BizSpark program. It received licenses for Microsoft's Visual Studio, SQL Server and Windows Server products.

"We're getting all the Microsoft software for free, so that's great for a startup like us trying to keep our costs low," said CTO and Cofounder Nick Ganju. "Some of these software packages can get pretty expensive so it's great to be able to keep our software free for the first few years."

Other products covered by the program include Office SharePoint Portal Server, BizTalk Server and Systems Center, with Dynamics CRM to be added soon. Startups also get a subscription to the Microsoft Developer Network and a Community Technology Preview of Microsoft's Azure cloud software announced last week.

To qualify for BizSpark, companies have to be privately held, less than three years old, have annual revenue of less than $1 million, and be developing an online service or hosted application.

They also have to be nominated by one of the partners Microsoft is signing up for the program, which include investment companies, university incubators and economic development agencies, said Dan’l Lewin, Microsoft's vice president for Strategic and Emerging Business Development.

The partners will be listed at the BizSpark Web site, expected to go live Wednesday, and startups can approach the groups and ask to be nominated, he said. Microsoft is also partnering with application hosting companies that can nominate startups and may offer them discount services, Lewin said.

Several other vendors offer startup programs, including Sun Microsystems, which offers cut price servers and its open source software.

Microsoft already offered some free software for startups, but it was for Express editions of its products or for more limited periods of time. The software licenses in the BizSpark program are for the full products with no usage restrictions, Lewin said.