NEW YORK • It may be one of this summer's most popular movies, but The Kissing Booth is not playing at a theatre near you.

Netflix released the teen rom-com on its streaming service with little fanfare in May and it quickly swelled into a stealth sensation.

"Fans found it, liked it and decided to pass it on to other people," said Vince Marcello, the film's writer and director.

"You can run commercials, you can do all the conventional stuff, but none of it is as powerful as people on their Twitter feeds saying, 'Oh my God, check this out, it gave me all the feels.'"

This user-generated strategy seems fitting given the DIY origins of The Kissing Booth.

In 2011, Beth Reekles, a 15-year-old in Wales, started posting chapters of the story on Wattpad, an online platform that allows amateur writers to read and comment on one another's work.

"It was easier to share it with total strangers online than people I knew," Reekles, now 23, said in an e-mail. "I was - and still am - quite self-conscious about my writing."

Readers responded with surprising ardour to the simple story. An awkward Los Angeles high schooler, Elle, falls for her lifelong best friend Lee's bad-boy older brother, Noah, after he is responsible for her first-ever kiss in the fairground attraction of the title.

The twist: Elle and Lee adhere to a strict set of rules for their friendship and one is that dating each other's relatives is forbidden.

"When I first wrote the story, Twilight had become popular and all of the young-adult stories I could find were paranormal romances," Reekles said.

"I just really wanted to read a regular high school romance and when I couldn't find that, I wrote my own."

After Marcello - who directed four films inspired by American Girl dolls - adapted the novel into a screenplay, Netflix became involved.

"We liked the idea that it landed somewhere between an R-rated teen film and younger-skewing fare like Disney Channel movies," said Mr Ian Bricke, the service's director of independent film.

"The trend in teen movies has been towards edgier, raunchier fare and it felt like there was a pocket that wasn't being spoken to."

That audience swooned for The Kissing Booth, with many watching it multiple times.

Netflix never releases the equivalent of ratings but it does report that of the viewers who have watched, one in three have seen it more than once, which is 30 per cent higher than the normal rate.

Joey King (Ramona And Beezus, 2010), who plays Elle, said there is something addictive about the movie.

"Young people on Instagram made these fan accounts and started hanging out with each other because they love and relate to it so much."

The movie has resonated with an older audience as well, Marcello said: "They're making comments like, 'I'm not sure I should be admitting this online, but I've watched this movie six times, and I'm 42 years old - oh, God, help me.'"

That was part of the plan all along. Marcello intended The Kissing Booth to be a nostalgia-evoking homage to the teen comedies of the 1980s and 1990s.

"Hollywood hasn't been making those kinds of films in recent years, and that's the reason we're so hungry for them," he said.

Not everyone has devoured The Kissing Booth with this kind of enthusiasm, however.

On the review-aggregator site Rotten Tomatoes, the film has received only one positive notice out of eight.

IndieWire slammed it as "a sexist and regressive look at relationships that highlights the worst impulses of the genre".

The movie's star shrugs it off.

"The problem with critics, not to bash on them, is that when they're watching a movie, they're looking for very specific things," King said.

"They are forgetting what it's like to watch a movie and not have to think about how happy you feel. The Kissing Booth just makes you feel good."

NYTIMES