Smartphone app Snapchat began letting users in the United States send money to friends by simply typing dollar amounts into new "Snapcash" messages

Smartphone app Snapchat on Monday began letting users in the United States send money to friends by simply typing dollar amounts into new "Snapcash" messages.

The new feature came from a first collaboration between Snapchat and Square, a mobile payments company headed by Twitter co-founder Jack Dorsey.

"The product you're seeing today is fast, fun, and incredibly simple," Snapchat, which has been eagerly looking to boost revenue, said in a blog post.

Those opting to use the new feature must store their at Square to carry out the transfers and must be 18 years of age or older.

However, about half of Snapchat users are reported to be 17 or younger.

Financial terms of the alliance between Snapchat and Square were not disclosed.

The new service was added as Snapchat works to boost the money-making capabilities of its popular app, which sees messages disappear shortly after being viewed.

Last month, Los Angeles-based Snapchat began weaving into the service.

The new ads were the first paid content at Snapchat. Users have the option of ignoring ads, which automatically disappear after being viewed or within 24 hours, according to Snapchat.

The startup said the reason for dabbling with advertising is simply that it needs to make money.

"Advertising allows us to support our service while delivering neat content to Snapchatters," the blog post said.

The introduction of ads came just weeks after a huge trove of evidently intercepted Snapchat images and videos were exposed online, raising fears about what may be revealed in messages intended to vanish seconds after beng viewed.

In what was referred to as "The Snappening," people who used third-party programs instead of the official Snapchat application had copies of supposedly transient missives squirreled away by hackers who began posting them online.

Snapchat assured users that the startup's servers were not breached, nor were they the source of the leaked images.

Snapchat rocketed to popularity, especially among teens, after the initial app was released in September 2011.