Braintree, an online payments provider, is debuting a set of new tools for mobile app developers that allow merchants to accept payments within a mobile app, rather than through a web browser. For background, Braintree powers and automates online payments for merchants and companies online. The company provides a merchant account, payment gateway, recurring billing, credit card storage, support for mobile and international payments, and PCI Compliance solutions.

The new offering from Braintree helps developers avoid PCI compliance issues by encrypting sensitive credit card data when it is entered by the user on their mobile device. The encrypted data is passed from the merchant’s server to Braintree for processing, and only Braintree can decrypt the information using a private key, preventing the merchant from being exposed to sensitive credit card data. The libraries support both mobile phones as well as tablet devices running Android, iOS, and Windows Phone 7 operating systems.

Braintree maintains that the customer entering the credit card information on the app is the last person to see it. Other mobile app payments solutions typically use a web browser masked as an app, says the company.

Braintree’s client list includes LivingSocial, 37signals, OpenTable, Fab.com, GitHub, Airbnb, Heroku, Engine Yard, Animoto, Shopify and HotelTonight. Braintree is processing more than $4 billion in annual credit card volume and is adding more than 100 new merchants a month. The company also raised $34 million in funding last year from Accel.