Ebay's PayPal division said on Tuesday it is acquiring StackMob, a company specializing in development tools for building mobile applications.

Terms of the deal were not announced. San Francisco-based StackMob, started in 2010, offers a custom API (application programming interface) that makes it easier for developers to connect mobile applications to backend platforms such as Salesforce and SAP.

StackMob offers a free basic service and more advanced subscription packages with service-level agreements, dedicated databases, API servers and support. The company's customers include Red Hat, Adobe Systems, Verizon and Urban Outfitters.

PayPal said StackMob will contribute to its development of new payment products as it seeks to diversify its payment processing by getting into retail stores.

Its "Beacon" technology uses a Bluetooth connection tolet customers pay for goods without even opening the mobile application once customers have "checked in" to a store. In August, PayPal announced a chip and pin reader, which allows small businesses to securely accept credit and debit card payments.