The Payments App Millennials Swear By Can this payments service catch on beyond its super-connected niche?

In preparation for this year's Burning Man festival, Ari Kalfayan, a Silicon Valley entrepreneur, went out and bought costumes for he and a friend. The total cost came to just under $1,000. But instead of reimbursing Kalfayan with cash, the friend paid him back using a smartphone app called Venmo. All it took was a few taps to send money between their accounts.

"I just found Venmo really easy to use for splitting costs for fun activities," says Kalfayen.

Small payments between friends is fueling rapid growth for Venmo, which lets people easily pay one another for everything from dinner to cocktails to paying rent. The idea is to free people from having to use cash or a check to split a bill.

Venmo handled $700 million in payments in the third quarter, 50% more than the previous quarter. The number of people who use the app is unclear. But it's telling that devotees are increasingly using Venmo's name as a verb — as in, "I'll just Venmo you" — much like Google, Facebook and Skype. Indeed, the app has become something of a must-have for Silicon Valley's young digerati, who regularly use the service to settle up between themselves after a night of bar hopping.

But it's also an area with huge competition from PayPal, Amazon, and Apple among others, all itching for the shot to process people's transactions and make a buck.

Venmo was founded in 2009 by former University of Pennsylvania roommates Andrew Kortina and Iqram Magdon-Ismail. Three years later, they sold their start-up for $26.2 million to the credit processing firm Braintree. EBay later gobbled up the entire company to build up its digital payments arm, PayPal.

When first acquired, Venmo had already gained a foothold among teen and twenty-something users. That trend has continued.

Being owned by a large company with deep pockets like eBay gives Venmo breathing room to focus on growth without having to worry so much about profits. The situation will become a bit more interesting next year after eBay spins off PayPal – and Venmo along with it- into a separate company.

Jared Fliesler, a venture capitalist at Matrix Partners and formerly a vice president at the payments startup Square, explained that Venmo's rise is tied to its ease-of-use. The ability to quickly find existing users and invite new ones by searching someone's virtual phone book and Facebook contacts helped with the app's growth.

"It was a simple product with a clear use case, so people got it and use it," Fliesler says.

Transactions appear in a section of Venmo loosely resembling Facebook's news feed that friends can see unless users fiddle with the settings to turn it off. To maintain privacy, Venmo never shows the actual payment amount, merely the payment's purpose, which users type in. The social networking aspect is by no means a critical feature. But it sometimes makes for short-lived entertainment.

"Most overpriced drink of my life," reads one Venmo update posted by one user going by the name Shira Papir. "For full body wax," reads another from a user identified as Roberto Sroka.

The big question for Venmo however is whether it's built to last. It competes with big guns like Amazon and Apple, both of which are pushing payments services. Additionally, Facebook is reportedly developing a service that would let users of its Messenger pay one another. If true, Facebook's payments service would be able to tap into the more than one billion people who already check the social network every month.

Marc Freed-Finnegan, who led the product development of Google Wallet for a year-and-a-half before leaving in 2012 to cofound Index, a retail analytics company, is skeptical about Venmo's prospects. He mentioned Square, a payments startup founded by Twitter co-creator Jack Dorsey, that got its start processing people's credit cards but has branched out with new services including a Venmo-like system called Square Cash. "There's already pretty strong competition from services like Square Cash at this time, which support pretty seamless payments between people," he says.

Oddly enough, PayPal, Venmo's sister payment service, is also a rival because it too lets users pay each other. But Venmo appeals to the younger demographic in a way PayPal doesn't.

Braintree CEO Bill Ready says he doesn't mind having two products in the PayPal family with similar features. He compares the situation to when Facebook acquired popular photo-sharing app Instagram. "You can take and share a photo with Instagram, or you can take and share a photo with the Facebook app," he says.

Eventually, PayPal will likely try to integrate Venmo into its other services to tap into those younger users. But for now, the Venmo team continues to experiment by introducing new features like "Venmo Nearby," which lets users know when friends are in the neighborhood.

Venmo isn't a serious money-maker. It generates some money by charging merchants, not consumers, for accepting payments through the service. But Ready maintains that building out Venmo with features like Nearby helps with attracting more users, and in turn, creates more opportunities to earn money. Says Ready: "You'll be seeing more and more of Venmo from us."