As US rapper Cardi B prepared the release for her latest song WAP, she checked off all the usual components of her promotional plan, including magazine covers, Instagram posts and a raunchy YouTube video. Then she added one more: OnlyFans, a site where people charge admirers for special access to videos and photos.

OnlyFans is closely associated with adult models. Many of its most popular creators are attractive women who use it to titillate men willing to pay a few extra dollars for a particular image. But Cardi B is part of a small but growing number of more traditional celebrities turning to OnlyFans to make a little extra revenue, raise money for charity or connect with followers in a new way.

In her first material for the site, posted on August 12, Cardi B uploaded a video from behind the scenes of her photo shoot for the cover of Elle magazine. A few weeks later, she shared footage from the making of her WAP music video. The post went on to generate several thousand likes on OnlyFans and almost US$1,000 in tips.

“When Beyoncé rapped about us on the Savage remix and Cardi B joined the platform, that’s when we really started to see the growth accelerate,” said Tim Stokely, 37, the company’s founder and chief executive officer. According to Stokely, OnlyFans is adding as many as 500,000 users a day and paying out more than US$200 million a month to its creators.

Along the way, OnlyFans has grown into one of the biggest media businesses hiding in plain sight. The company has 85 million users, upwards of 1 million creators, and will generate more than US$2 billion in sales this year, of which it keeps about 20 per cent.

That puts the site on track for US$400 million in annual net sales – dwarfing Patreon, a platform devoted to helping creative types monetise their work, which is valued at more than US$1.2 billion. “OnlyFans is revolutionising creator and fan relations,” Stokely said.

What OnlyFans customers crave, said Stokely, is a level of interaction and intimacy with the creator that they don’t typically get on Instagram or Twitter, where celebrities tend to share the most manicured version of themselves.

But to keep gaining more mainstream appeal, the company will likely have to shake off its reputation as a den of online debauchery and assuage safety concerns about the site.

Its first successful creators were primarily alluring women. Jem Wolfie, a fitness model and chef in Australia, quickly earned more than US$1 million on the site by sharing spicy videos and photos of herself (Wolfie did not respond to an interview request).

Another popular account, Aellagirl, is run by Aella Jones, a devout Christian turned web siren. New subscribers are greeted by a naked photo of her captioned: “Welcome to the cult, we have boobies.”

“I like that it only takes 20 per cent, which is much lower than the prior industry standard of a 50 per cent minimum,” Jones wrote via email.

“I like that it’s much more strategic and disconnected than live camming was; live camming requires energy, personable charm, whereas OnlyFans really rewards things like good marketing ability and clever pricing techniques. I also get to interact with my fans throughout the day for very low effort, instead of having to put a lot of time in to get ready to do a full ‘show’.”

Many of the top creators spend a lot of time communicating directly with fans. Visitors are encouraged to provide a tip if they want a personalised message.

Stokely has tried for years to get all types of creators to use the site. “It works as a great bolt-on to free social media,” he said.

“One of our selling pitches is, ‘Look, you’ve got a million followers on Instagram, if just 1 per cent of them pay for Only Fans …’” The average creator charges about US$12 per subscriber. By Stokely’s maths, if 1 per cent of Kim Kardashian’s Instagram followers paid for OnlyFans, she’d make US$23 million a month on the site.

Until this year, the business was growing at a steady pace. The pandemic boosted it to new heights thanks to people who are out of work and looking for a new way to make money at a time when everyone is stuck at home and desperate to be entertained.

Strippers and porn stars eager to make up for their lost earnings have flocked to OnlyFans, while regular strip-club customers have found a new place to get their jolt of excitement.

But it isn’t just the adult entertainers who have given OnlyFans a try. Musicians The Dream and Swae Lee have used it to promote new music.

Actress Bella Thorne hopped on the site and made US$1 million in one day. Drag queen Shea Couleé has filmed herself doing make-up before performances. And social media personality YesJulz has used it to share fitness workouts.

After hearing about the service from some friends, Cardi B, a former stripper and reality-TV star turned multiplatinum rapper, reached out to her record label and to OnlyFans about setting up an account. “She had a vision for it,” said Julie Greenwald, the co-head of Atlantic Records. “For her, she thinks, ‘Who are my fans and how do I make sure I am delivering?’”

Stokely is now rushing to capitalise on the site’s growing popularity. The company, which is based in London, is setting up new offices in Asia and Latin America.

It is also planning to create a new online streaming service called OFTV, which will feature exclusive content such as creator-driven series and personal interviews with OnlyFans personalities.

And how will OnlyFans appeal to mainstream performers who might blanch at the thought of working with a site associated with adult entertainment?

“I’d just repeat that since we launched, we’ve always welcomed all creators,” said Stokely. “The creator community is incredibly diverse. There are just so many creators from so many genres, whether it’s gaming, fitness, fashion, beauty.”