Attorney General Maura Healey has drawn the ire of die-hard sports fans by saying she is “reviewing” the legality of DraftKings, a popular Boston-based fantasy site.

“It’s a game. She should just leave it alone,” said Tony Savageau, 51, of ?Mansfield. “There’s money involved, but I’m not looking to retire from this. We just want to have some fun.”

David Baggaley, 47, of Hancock, N.H., agreed, saying he considers the chance to win big cash prizes on fantasy sports to be in “a different category” than regulated gambling.

“I think it should be left alone,” Baggaley said. “There’s too much regulation in a lot of things.”

The company, which lets its 3 million active users participate in fantasy sports contests for a single day or week instead of over the course of a season, shells out cash prizes to users who pick the best teams.

DraftKings, which launched in 2012 and has 260 employees in Boston, New York and the United Kingdom, has been valued at more than $1.2 billion, according to Fox Sports.

“We are a US-based skill games company, and all of our contests are operated 100 percent legally under United States and Canadian law,” the company writes on its website.

“The US Government and 45 of the 50 states consider fantasy sports a game of skill.”

In order to participate in the range of free and paid contests DraftKings offers — which aren’t available to residents of Arizona, Iowa, Louisiana, Montana and Washington — users must be at least 18 years old.

The budding company has been pouring millions into TV ads and has committed to spending a combined half a billion dollars in advertising on Fox Sports and ESPN over the next several years.

Healey, a vocal casino opponent, said yesterday she is looking into whether the site is operating legally, a spokeswoman confirmed.

When contacted by the Herald, a DraftKings spokesperson responded with a statement, saying the company is “happy to work with the Attorney General to answer any questions she may have about our industry.”

The fantasy sports market has exploded in recent years with an estimated 57 million people in the U.S. and Canada participating, according to the Fantasy Sports Trade Association.

The association’s chairman, Peter Schoenke, defended DraftKings yesterday, pointing out that fantasy sports have been “a major driver of fan interest and engagement for decades.”

“These are skill-based games that match sports fans against each other in a contest of sports knowledge and strategy that is fundamentally different from wagering on the performance of an individual player or the outcome of a particular game,” he said.

Boston College business professor Richard McGowan is predicting Healey will “run into a lot of people who will say ‘I don’t think there’s anything wrong with it’ and they will try to find ways to get around her.

“If she determines that it’s illegal,” he added, “I can’t imagine that they won’t go to court to fight this and that’s going to be an interesting legal battle.”