family from Melbourne who took the concept behind social-media photography and reinvented it for music.
"Basically, you sing into your phone and it creates a song around what you've sung," said Joe Russell as young music fans streamed into Jam's booth in the SXSW trade show hall Thursday to spend a minute each trying out the app.
"You don't need to play an instrument or even sing all that well," he told AFP. "You just have to sing into your phone and pick a (musical) style and it will created a song in that style, an original song."
But there's more: users can upload their recordings onto Jam -- just as Instagram or Hipstamatic photographers can do with their photos -- for any and all to see, and the most popular tunes can wind up on Jam's own hit parade.
More than 260,000 users, mostly in the United States, have so far downloaded Jam from the iTunes store, the Russells said, adding that work is underway on Japanese and Chinese versions for the promising Asian market.
"It's meant for people who don't necessarily create music in their day-to-day lives," said Joe Russell, 33, general manager of DreamWalk Interactive, a startup founded by the tech-minded siblings.
"It enables them to create music when they wouldn't have otherwise. It's cheating" -- in the sense that users never need to learn an instrument or really know how to sing -- "but every can make music now. That's the good thing."
Jam is representative of the way technology is driving the future of music, undermining the traditional business model whereby musicians had to struggle to get the attention of taste-making record labels to build their careers.
Only in this case, the musicians can be anyone with a smartphone -- even if they can't sing very well, because Jam contains its own version of Auto-Tune, the pitch-correcting vocal software commonly used by big-name artists.
"We had a pretty clear idea going into the project (of what Jam would be like) and we had some great guys working on it," said Sam Russell, 27, who oversaw the "difficult" six-month writing of the software.
Once done, a completed Jam song can be shared with other users who can, in turn, vote for their favorites -- with the songs getting the most likes finding their way into Jam's Top 100 chart.
On Thursday the number-one song was a jumped-up dubstep take on Justin Bieber's "As Long As You Love Me" by one Ayanna Snookie Perez, which had 1,241 likes out of 86,895 listens.
Many of the songs are cover versions, and it remains to be seen if any record labels or music publishers complain about copyright infringement -- although performing and posting one's favorite pop tunes on YouTube is commonplace now.
The basic Jam app is free to download, but users can pay for extra features and music styles packs, much as Hipstamatic users can buy additional filters and virtual lenses to widen the creativity of their images.
While they're currently looking for investors, the Russells -- who previously developed a GPS treasure hunting platform -- say they have no interest in selling Jam or their company for the time being.
And while they don't know of any actual stars currently using Jam, they don't rule out an unknown "Jammer" breaking into the big time one day. "We're waiting for the first signing as a result of Jam," Joe Russell said. "It's coming."