One year ago, USA Today opened up its massive database of articles, reviews, census figures, and sports salaries to the public. The newspaper provided open and well-documented APIs to software developers, but access was limited to personal and noncommercial use.

Last week the newspaper quietly changed that, offering commercial licensing of its data on a case-by-case basis. Premium licenses would remove rate limits and caps for data-hungry programs, too. That means USA Today can make money selling its data and app developers can make money using it.

The newspaper also lifted commercial restrictions from its collection of census data, one of its most popular APIs. While the data is publicly available, USA Today assembled it from multiple sources and structured it in a predictable, developer-friendly way.

Stephen Kurtz, the newspaper’s vice president of digital development, said the move is in response to requests from developers looking to build paid apps with USA Today’s data. “Most of them are mom-and-pop shop — two guys in a garage, or one guy in a garage — mashing up our content with other content. The reviews APIs are really popular, and they’ve been mashed up with other open APIs out there, like the Netflix API, for example,” he told me.

“We encourage that, and they give us good feedback of what they’d like to see and how they would like the API to grow. So for us, it’s very symbiotic.”

Kurtz said he has not decided on a standard pricing model — he wants to gauge demand first.

It’s an intriguing side business, another way for the paper to profit from its deep well of content. Plus, it puts the USA Today brand in more places. In a blog post, developer Ethan Hamlin explained it this way:

Our developer service was launched with the hope of expanding the ways people discover, engage with and communicate about USA TODAY content, and we view this as an important next step.

Both the Articles and Reviews APIs offer robust methods to access USA TODAY story briefs dating back to 2004. In exchange for opening these APIs to the public, we hope to increase our web audience via referrals back to our pages…

The Guardian, with its Open Platform, is the only other major newspaper I know of that offers the “freemium” model of access: free access to headlines and article excerpts; free access to full articles with embedded advertising; and paid access to articles with no advertising or data caps. (The Guardian’s Hack Day 2011 is today, by the way.)

The New York Times also provides extensive, well-documented APIs but no paid access to full article content. NPR provides an open API but grants full access only to dues-paying member stations.

Kurtz said he plans to release new APIs in the coming year, including for presidential polling data. Developers could build something like electoral-vote.com that automatically pulls in polling data, for example. Kurtz also plans to release an API covering years of data on the Olympic Games, which could be particularly lucrative for app developers next summer.

Kurtz is still deciding whether to charge for premium access to those datasets. “We’ll hopefully lean to be open when we can, but we also understand the value of this data,” he said. “I have to be honest with you — we’re kind of stepping into this, seeing what the demand is, and then I’m sure we’ll evolve our model from there.”