It’s been a year and a half since “Hadestown” was an Off Broadway hit, but fires are still burning for the folk-rock musical. They’ve blazed up online, where the show’s streaming success points to digital platforms as an increasingly reliable tool to help producers move a show from buzzy blip to Broadway contender.

A live recording of the New York Theatre Workshop production, which ran May 6-July 31, 2016, dropped in October, and since then the album had passed 680,000 track streams, according to Nielsen SoundScan. That’s notably more than the tally for established musicals like “Come From Away” (332,000) and “War Paint” (218,000).

“It was like a little Off Broadway show last summer,” marveled Mara Isaacs, one of the commercial producers shepherding the show’s further life. “Where did all these people come from?”

“Hadestown” is just the latest example of new musical-theater titles and talent gaining traction through the likes of You-Tube, Twitter and Spotify — especially with work that appeals to younger-skewing audiences who are both theater fans and digital natives.

Songwriting partners Kait Kerrigan and Brian Lowdermilk, whose musical “The Mad Ones” is playing at Off Broadway’s 59E59 Theaters, have a YouTube channel that’s racked up more than 7 million views. (The most popular song, “Run Away With Me,” sung by Aaron Tveit, now stands at 1.1 million.) Kerrigan estimated the fanbase to be about 65% female, with 60%-70% of those in the 15-30 age range.

Prior to “The Mad Ones,” the pair has had only one show, all-ages musical “Henry and Mudge,” play Off Broadway — and that was back in 2006.

“At this point we have to assume that almost everyone who has come into contact with our work encountered it online,” Lowdermilk said.

For “The Mad Ones,” that translates into a spike in younger theatergoers buying tickets at 59E59, according to the venue’s marketing director, Kirsty Gaukel. For Kerrigan and Lowdermilk, it means a quantifiable fanbase interested in the team’s developing projects, like the immersive house-party musical “The Bad Years.”

The songwriters admit there’s no strategy to their digital presence, other than turning to online as a cost-effective, accessible way to connect with fans. Producers of “Dear Evan Hansen,” on the other hand, had a clear blueprint for using streaming to build buzz as the show made its way from D.C.’s Arena Stage in 2015 to Off Broadway’s Second Stage in the spring of 2016 to Broadway later that year.

Prior to the Off Broadway run, the “Hansen” team released a streamable (but not downloadable) recording of the song “Waving Through a Window,” exclusively on the show’s website. By the time it was taken down just before the Broadway opening, it had racked up more than 1 million streams, according to Situation Interactive, the agency that handles digital marketing for the musical.

It was all part of a plan that featured fan-engagement pushes like personalized tweets, a surprise tune drop and a digital listening party for the cast album. The strategy meshed well with the already healthy digital presence of songwriting team Benj Pasek and Justin Paul, who built up a youthful audience with fan-favorite musical “Edges” and their work on NBC’s “Smash.” (On Nielsen SoundScan, “Dear Evan Hansen” now weighs in at a whopping 118 million track streams.)

For “Hadestown,” which recently wrapped up a run at the Citadel Theater in Edmonton, the cast recording’s digital popularity came as a surprise, likely seeded over a long developmental period that included a 2010 concept album for which the show’s creator, musician Anaïs Mitchell, enlisted guest stars like Ani DiFranco and Justin Vernon, the front man of band Bon Iver.

Now that the “Hadestown” fanbase has been established, it might just carry the musical to Broadway. “That certainly is a good destination for it,” Isaacs said.