Skrillex is one of this year’s FreeFest headliners. (Tracy A. Woodward/The Washington Post)

Other featured performers include majestic synth-pop group M83, bearded classic-rockers ZZ Top, reunited local indie-rock heroes the Dismemberment Plan, Americana breakout stars Alabama Shakes and pop polyglot Santigold. Nearly 50,000 free tickets will be given away online — and surely disappear within minutes — beginning at noon on Friday, Aug. 24 through TicketFly.

This year’s lineup is particularly diverse for a festival that prides itself on offering something for everyone. If Coachella is the hipster festival and Bonnaroo is the hippie festival, FreeFest is the festival that can’t be pigeonholed.

“The fact is, these days all kinds of people like all kinds of music,” Seth Hurwitz, chairman of promoter I.M.P. and producer of the festival said in a phone interview on Monday. “People like variety. The common theme here is to try to present acts that are the real deal, whether they’re brand new or returning war heroes like ZZ Top. That’s the excitement of not worrying about selling tickets.”

Rounding out the lineup on the two main stages: piano-pop mainstays Ben Folds Five, soul newcomer Allen Stone, bluegrass upstarts Trampled By Turtles, punchline rap group Das Racist, Baltimore synth-crooners Future Islands, psych rockers Portugal. The Man and local troubadour Justin Jones.

This will be the festival’s fourth year at Merriweather Post Pavilion after relocating from Baltimore’s Pimlico Race Course, cutting down from two days to one and eliminating admission fees. The Dance Forest, a stage focusing solely on electronic music, will also return with acts including Above & Beyond, Porter & Zedd, Thomas Gold, Nervo and local up-and-comer Alvin Risk.

Hurwitz says since getting rid of tickets is never a problem, it lets him wait until the last minute to finalize the lineup.

“It’s like playing chicken, booking this thing,” he says. “You can wait until about six weeks out to add the latest [acts] that aren’t playing other festivals. That’s the cool thing about it. Most festivals have to book six to eight months out so they sell tickets, so the stuff they book is kind of eight months ago.”

It can also lead to happy accidents, like ending up with Rock and Roll Hall of Fame inductees ZZ Top on the same bill as dubstep DJ Skrillex. Hurwitz said that ZZ Top was originally booked as an opener for a Jack White show at Merriweather Post Pavilion, but then White’s schedule opened up and headlining FreeFest became a possibility. During negotiations, Hurwitz said White’s handler asked him, “Well, Jack wants to know if ZZ Top would still be on the bill.”

As in past years, the concert will be general admission and the pavilion area will be cleared after each act in an effort to let as many different people as possible get up close at some point during the day. For those looking for a sure way to score tickets, “Freemium Packages,” which include admission to the festival, a charitable donation to Virgin Mobile USA’s youth homelessness initiatives, a FreeFest T-shirt and a souvenir cup that comes with free fountain drinks throughout the festival will be available for $49.50.