eBay has bought highly rated Braintree for $800 million in a move to boost the mobile payment credentials of its PayPal unit.

Although only founded in 2007, US firm Braintree has rapidly built a significant reputation as a processor of mobile and online payments.

The acquisition has been mooted for some time but speculation has picked up this week.

Braintree is processing about $4 billion in mobile payments annually, equivalent to one third of its total volume, according to a recent interview given by CEO Bill Ready with Pando Daily.

The mobile part of its business has grown rapidly since the acquisition of Venmo, a m-pay app.

Meanwhile, PayPal has also seen strong growth from mobile payments. Its parent said it expects PayPal to generate m-pay volumes of more than $20 billion this year.

PayPal is pushing hard in the mobile market, both in online (mobile and PC) as well as physical payments. The Braintree deal will help more with the former ambition.

The deal will boost the payment giant’s reputation among developers and bring in some innovative spirit, say observers. The idea is for the new acquisition to continue to operate separately from PayPal.

Braintree’s business is processing payments rather than providing wallets for companies. Its clients include Airbnb and Uber.

The Braintree deal is expected to close in the fourth quarter. The acquisition is expected to have an immaterial impact on eBay’s revenue guidance, although it will have an impact on its adjusted earnings outlook.

PayPal president David Marcus (pictured) said in a blog that PayPal was already delivering innovative services to merchants. “A lot of other companies claim they’re doing these things, too. But in the crowded payments space, most have a long way to go before they actually deliver useful solutions at the scale that’s required.

One company delivering these solutions today is Braintree. In a very short time, Braintree has built impressive mobile payment solutions that handle transactions in 130 currencies in more than 40 countries. Mobile developers love Braintree’s tools and the great hands-on service that they offer.”