This year’s Billboard Hot 100 Music Festival is stacked with fun.

Rapper Big Sean and EDM wiz Zedd will headline the festival Aug. 19 at Northwell Health at Jones Beach Theater, with Demi Lovato set to make a special appearance, while DJ-producers Major Lazer and Marshmello set to headline Aug. 20. And after setting Jones Beach Theater attendance records in 2015, when it became the first event to add a stage on the beach, this year, it will add a fourth stage, featuring New York-area acts on the plaza at the main entrance.

“The tone and tenor of this year’s festival is to be summer’s biggest party,” says John Amato, president of Billboard, the music magazine that produces the two-day event with Live Nation. “We picked acts that have a party vibe, who are fun and upbeat. . . . It will be like a radio show on steroids.”

Organizers say they want the Hot 100 fest to be different from most festivals currently on the scene. “I love Chance the Rapper and I love the Red Hot Chili Peppers, but you can see those acts at festivals at any number of cities, sometimes you could see them several times in the same market,” Amato says. “We want to give people acts right when they’re starting to take off. We are picking people who we are thinking will be the next big thing.”

Echosmith certainly fits all of the Hot 100 fest’s requirements.

Best known for their hit “Cool Kids,” the California rockers are set to release their sophomore album “Inside a Dream” (Warner Bros.) at the end of September, as their new single “Goodbye” starts climbing the pop charts on the strength of the enthusiasm of the band’s young fans, who have given the Sierota family nearly 150 million YouTube views already.

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Echosmith singer Sydney Sierota says she gets a lot of inspiration from playing shows with younger audiences. “It makes it a lot of fun,” she says. “It’s like hanging out with our friends every day. We’re going through all the same things.”

As much as Echosmith is excited about its new songs, Sierota says not to expect too much unreleased material in their Sunday set beyond “Goodbye” and maybe one other new song.

“We want to play it and the fans are ready to hear it,” she says. “But timing is important, too. I don’t think it would be too cool to play all these songs they’ve never heard before.”

After all, this will be many fans’ first chance to see Echosmith since Sierota’s brother Jamie, the band’s guitarist, left the band to spend more time with his family. “Inside a Dream” shows the band’s new sound, which focuses more on Sierota’s solo vocals rather than the familial three-part harmonies. “At first, it was very difficult,” she says. “But we just started writing to see what happens and it came out naturally. . . . It was cool because we had so much freedom to explore who we were. It was so much fun to try things.”

Billboard’s Amato says the festival will continue to try new things, like this year’s local stage. It may also expand next year to Los Angeles as well as another city outside of the country that is close enough to Long Island that would allow several headliners to play both festivals in the same weekend.

“We couldn’t be happier with our Long Island roots,” says Amato, who has moved to Melville since launching the festival in 2015. “We finally brought the kind of festival Long Island deserves to Long Island. We’re very happy with the way everything has turned out.”