Lots of companies start out offering free products on the Web and then move to premium, paid versions.

Seattle's Tableau Software is going the other direction. After building a strong business selling data visualization tools to corporations, government agencies and non-profit organizations, Tableau decided to give away a free version for use on the Web.

The software, available today at Tableaupublic.com, is a set of tools for building interactive graphics based on spreadsheet data. Interactivity depends on the features added, but these are the types of graphics that dynamically change as you click to analyze and explore the data.

Graphics built with Tableau Public can be embedded into blogs and Web sites and shared online. Also made available are the underlying sets of data; if users want to restrict use of the graphics or the data they'll have to upgrade to paid versions of Tableau that start at $1,000.

Chief Executive Christian Chabot hopes that Tableau's free tools will help data become a "first class citizen" on the Web, similar to the way tools such as YouTube advanced online video.

"Data on the Web is like video in 1997," he said.

Chabot, 38, co-founded Tableau after its tools were initially developed with Defense Department funding at Stanford University. The Fremont-based company moved to Seattle in 2003 and now employs 105.

Sales grew 55 percent last year to more than $20 million. Chabot expects to hire another 50 people this year and offer shares in the company in three to five years.

"Our plan is to take it public and employ thousands of people in Seattle,'' he said.

In the meantime, Chabot's hoping Tableau's free tools will raise awareness of its products and help people better understand data.

Sharing a free version online was encouraged by Adobe co-founder Chuck Geschke, who joined Tableau's board in 2007, Chabot said.

Chabot is especially enthusiastic about seeing Tableau Public used to analyze data the federal government is increasingly sharing through new transparency initiatives.

"It is for the public at large to use with public information for the public good,'' he said.

Here's a Tableau Public graphic that Chabot built using TechCrunch data to show where VC's funded companies in 2009. You can explore the graphic and change the display by clicking on the various modules: