Snapchat's Snapcash feature lets users send money via Square First, it was photos then video text. Now, add money to the list of things people can send to each other via the Snapchat app. The Los Angeles start-up announced a partnership Monday with payment service Square that allows Snapchat users to choose a friend, type in an amount to send and press one button to complete the transaction. Snapchat users must sign up with Square, which stores the debit card details that enable the transfer. "The product you're seeing today is fast, fun and incredibly simple," Snapchat said in a statement. The feature is available to adults in the U.S. "Snapcash" is the first time Square Cash, which allows money to be sent via email, has been integrated into another app. Bringing Square into an app that millions of millennials turn to everyday should the raise the profile of the San Francisco start-up and give it a better chance of stealing away users from the popular money transfer apps Venmo and PayPal. Person-to-person payments via smartphones and tablets are a small portion of all mobile transactions, but are growing fast, Forrester Research said in a recent report. By 2019, such payments are expected to reach $17 billion a year in the U.S. Snapchat declined to discuss terms of the partnership. The company has been experimenting with ads as a way to generate revenue, but the payment tie-up suggests the app could become a destination for purchases as well someday. Discussing his app's simplicity at an event last week, Snapchat Chief Executive Evan Spiegel emphasized the value of unlocking something meaningful with just one button. "That's the only way to drive adoption of the product," he said.