The podcast “Limetown” ended its first season topping the charts on iTunes, but well before the serialized audio program had finished, its creators Skip Bronkie and Zack Akers had signed a representation deal with WME. If the creators have their way, “Limetown” — about a fictional town where 300 people mysteriously disappear from a Tennessee neurological research facility — will soon be translated to the small screen.

Agencies are feverishly combing through those Apple Podcasts charts to snap up clients, aiming to break out the next TV or film hit or launch the next business. 2017 was the biggest year yet for podcasts, which have exploded in popularity recently. Apple Podcasts, as the recently re-branded platform is now known, features more than 500,000 active podcasts, including content in more than 100 languages. Where just five years ago only 12% of Americans 12 and older listened to podcasts in the last month, that audience is now up to 40%, or roughly 112 million people, according to a survey by Edison Research. A majority of Americans — 6 out of 10 — are now familiar with the term “podcasting,” compared with 46% in 2012. Fifteen percent – or 42 million people – have listened to a podcast in the past week.

Podcast makers — and those who sign them — hope that cachet and built-in audience will follow.

When Bronkie and Akers made “Limetown” in 2015, their expectations were low: With some success, they hoped to find new collaborators for future podcasts. “That definitely evolved when all these doors started opening for us, and the ability to adapt in another medium was really interesting for us,” Bronkie says.

Now they’re flag-waving advocates of the medium. “It’s starting to legitimize itself as a real form,” says Bronkie. “There are a lot of seriously talented people in this space now that are doing seriously talented work. It’s not just a casual thing that you can dismiss. There’s real material here that’s just as creative as any TV show or movie.”

The runaway success of “Serial” in 2014 ushered in a boom in audio programs, both fiction and nonfiction, that have now become a rich source of expandable IP. The major talent agencies — WME, CAA, and UTA — quickly dedicated agents to find new clients and broker development deals for podcast makers. In addition to serving as IP incubators, podcasts are also an increasingly lucrative stand-alone business. Talent agents have also helped broker terms of distribution for growing podcast networks and arranged tours for well-known offerings like the progressive podcast “Pod Save America.”

There’s also money to be made on the advertising front, as marketers have flocked to the platform. Accounting and research firm PwC projects that by the end of the year, podcast advertising revenue will rise to $220 million, up from $119 million in 2016 and $69 million the year before that.

“We’re really in the early stages of what I believe is going to be an explosion in this space,” said Sam Wick, head of ventures for UTA. The firm represents personalities like Ira Glass (“This American Life”) and “Serial” host and executive producer Sarah Koenig.

Koenig’s podcast became perhaps the most prominent podcast to be picked up for television development. Chris Miller and Phil Lord, directors of “The Lego Movie” and “21 Jump Street,” in 2015 optioned “Serial” for a Fox 21 cable-television series.

Others have quickly followed: Last Halloween, Amazon released “Lore,” based on the hit podcast by Aaron Mahnke about historical, supernatural tales. The digital giant has also ordered two seasons of “Homecoming,” a political thriller produced by Sam Esmail (“Mr. Robot”) that will star Julia Roberts. “Alex, Inc.” a workplace comedy starring Zach Braff, will debut on ABC this spring; it’s based on “Startup,” a podcast that chronicled the rise of Gimlet Media, one of the most prolific companies making podcasts. “Throwing Shade,” a podcast on politics and pop culture hosted by Erin Gibson and Bryan Safi, has been airing on TV Land since January, and comedian Marc Maron’s podcast became a four-season TV show on IFC that ended last summer.

And on the film side, Annapurna Pictures has optioned an episode of “Reply All” for a feature directed by Richard Linklater and starring Robert Downey, Jr.

Mahnke, the Boston-area writer who created “Lore,” who had written a handful of books before becoming an audio storyteller, never envisioned that his childhood fascination with the supernatural tales would eventually lead to producing a television series. “It’s a super ancient thing – it’s just storytelling,” says Mahnke. “The campfire is just the glow of your cellphone screen.”

But so far no podcast has converted its audience into broad success on a larger media stage. Lord and Miller’s “Serial” adaptation stalled creatively and is no longer in active development. According to research firm Parrot Analytics, of the five original Amazon dramas released in 2017, “Lore” ranked third in terms of audience demand within 30 days of release — well behind “Z: The Beginning of Everything,” which was canceled in September.

Dawn Olmstead, co-president of Universal Cable Productions, which is producing “Homecoming,” said that no podcast is a sure thing without strong development.

“Sometimes a property won’t properly translate to a different medium,” she said. “Sometimes the people who are developing and doing the adaptation aren’t a swing and a hit.” But that issue is the same for all source material in any media being adapted to TV. “That has nothing to do with the fate or nature of podcasts.”

Olmstead expressed confidence in Esmail and the “Homecoming” source material. “There are some things that are going to be really right for television to be adapted from podcasts. ‘Homecoming’ is one of them.”

A podcast, according to media consultant Brad Adgate, can provide proof of concept and a legitimate starting point for a series in the Peak TV era.

“Why not give it a shot?” Adgate said. “When television came into existence, there were radio shows that migrated to television. Podcasts have become very popular. There are audience figures to look at, and you can figure that those people who are appointment listening to podcasts will at least test it out on television or streaming video.”

And a podcast doesn’t necessarily have to mean a traditional series. Rather than build a new program inspired by Jessica Williams and Phoebe Robinson’s “2 Dope Queens” podcast, HBO effectively gave the two comedians additional resources to stage souped-up episodes of the podcast to air as comedy specials.

“Our approach is don’t mess with something that works so beautifully and so simply,” said Nina Rosenstein, executive vice president of HBO Entertainment. “It just seemed like a no-brainer — of course we would do it this way.”

Thinking beyond simply translating the podcast to the screen may prove more successful. WME has also helped putting together scripted and non-scripted content with the aim of creating a meaningful derivative business. “36 Questions,” a podcast musical released in July, is another idea conceived by Bronkie and Aker and it stars Jonathan Groff, fresh off “Hamilton” and “Frozen.”

Jacquie Katz, a CAA agent, said her firm had begun representing podcast creators about two years ago, recognizing the potential to translate the IP into other mediums.

“We as a company realized that the landscape in TV and in film really was starting to be based on IP in so many capacities,” Katz said. “Podcasts were this interesting, lesser-tapped space.”

Signed podcast makers have access to CAA’s creative and business development departments where the agency can help them with strategic planning and marketing. Some podcasts, she said, won’t be developed into other mediums, but they might go on tour.

Live tours for popular podcasts typically stop in major cities, which tend to have the largest concentrations of listeners. Former Obama speechwriter and WME client, Jon Lovett, for instance, recently stopped in Los Angeles to host a sold-out taping of his popular podcast, “Lovett or Leave It,” a politics-themed show.

Chris Giliberti, head of multiplatform development at Gimlet Media, said he is excited to be part of a still-maturing industry that has “tons of headroom for growth.” Obstacles still remain, however, including a lack of awareness and a distribution infrastructure that is still catching up. “As dashboards digitize, I think we’ll see a lot more audiences come on board,” he said.

WME’s Ben Davis said distribution is another area in which he helps clients.

“As the shifting media landscape continues to evolve, we’re interested in any area in which our client can own their distribution and own the direct line to their audience,” he said. “It changes the way that they can promote projects, it changes the way they can incubate intellectual property.”

Gimlet Media, a CAA client, has seen four of their programs get picked up for development, becoming something of an IP farm for the agency. (“Homecoming,” “Startup,” and “Reply All” are Gimlet productions.)

That’s not by accident. Giliberti leads efforts to adapt Gimlet’s programs into other mediums. The former entertainment business consultant said podcasts become attractive to producers because they often come with a dedicated following and the non-visual format fully commands a listener’s attention.

“We really have just this incredible trove of super high quality stories,” said Giliberti. “With audio storytelling there’s just an incredibly high bar for the maintenance of attention. You don’t have something for folks to look at.”

Daniel Holloway contributed to this report.