When Frank Ocean’s album “Blonde” came out in August, it went straight to No. 1 and became the talk of the music business because it was released completely outside the usual channels of the recording industry. The mystery was how Mr. Ocean and his team did it.

One answer was revealed on Sunday in an online ad promoting “Blonde” as one of the most acclaimed releases of 2016 and noting that it was “powered by Stem.”

That service, which began only a year ago, has quickly become a player in a fast-growing corner of the music industry: online platforms that cater to independent artists by distributing their music to streaming services and organizing the many strands of royalties that accumulate from fans’ clicks.

Stem, founded by three 20-somethings in Los Angeles, has attracted a clientele of young artists who operate independently yet tend to collaborate frequently with other acts, some of them stars. For them, Stem’s attraction is its ability to easily manage the complex “splits” — the divvying up of royalties among multiple parties — that result from such collaborations. Stem Disintermedia, the company behind it, has raised $4.5 million from investors, including Upfront Ventures and Scooter Braun, who is the manager for Kanye West and Justin Bieber.