After daily fantasy sports company DraftKings debuted its sportsbook offering in August, rival FanDuel didn’t wait long to launch its own.

FanDuel has soft-launched its sports betting app called FanDuel Sportsbook with plans to officially go live by the end of the week — just in time for NFL season. The app will be available to the public, but only users who are physically located in the state of New Jersey will be able to place bets.

Fortune got a demo of the new app, and it offers a variety of features, including seven different payment options, future betting lines, and in-game wagering that allows users to bet on live games.

After the Supreme Court cleared the way for states to legalize sports betting, daily fantasy sports companies got to work immediately. Why? Sports gambling will account for a huge chunk of their business.

While DraftKings told Fortune that its product team began developing the app a whole year prior to the Supreme Court decision, FanDuel had to wait until after the decision was announced. The Supreme Court ruling happened around the same time as FanDuel and Paddy Power Betfair were finalizing their acquisition talks.

Just a week after the bombshell Supreme Court ruling, the Ireland-based gaming giant agreed to acquire FanDuel in a deal that reportedly values the combined business at more than $1 billion. As a result, FanDuel had to develop and release the app in a matter of six months in order to be ready for football season.

“We had to ramp up very quickly,” Nik Bonaddio, Fanduel’s head of product, told Fortune.

Paddy Power’s technology powers the FanDuel Sportsbook app, and the pricing and betting engines are the same ones used in Paddy’s existing sports betting products. FanDuel, however, spent time to design the app and make it more appealing to an American demographic.

“It was about putting egos aside and creating the best product we could develop with both of our skill sets,” Bonaddio said.

Rival DraftKings debuted its sports betting platform an entire month before FanDuel. Bonaddio explained that the process has taken longer than he wanted, but FanDuel was deliberate in working closely with regulators while developing the app.

“If regulators say, ‘Jump,’ we say, ‘How high? We could’ve taken the approach of doing first and asking for forgiveness later, but it’s just not worth it for us to do that,” he said.

The sentiment was echoed by FanDuel CEO Matt King who told Fortune that his company treads carefully when it comes to regulation. “We’ve always taken a more conservative approach to the point where we deliberately didn’t innovate in certain areas because we weren’t sure if it would be deemed acceptable,” he said.

On the eve of the NFL season kickoff, FanDuel is ramping up to launch its sports betting offering. Though the company has been beta testing its app for a few months by asking for user feedback and doing anecdotal interviews, it remains to be seen how it performs in the wild.

“There are two stages of anxiety,” Bonaddio said. “The first is, ‘Oh my God, how will we build this,’ and the second is ‘Oh my God, did we build the right thing? We’re now entering the second stage.”