In a move designed to bolster its mobile wallet, PayPal, the online and mobile payments arm of eBay Inc., has acquired mobile app developer Duff Research. EBay declined to reveal the purchase price.

“Last year, we began developing all of our products with a mobile-first mentalityto drive engaging, simple customer experiences,” writes James Barrese, PayPal’s chief technology officer, on the official PayPal blog. “As PayPal continues to be a leader in mobile payments, we are looking for talented engineers with proven mobile experience to help us imagine, develop and deliver products our customers love.”

The Duff Research team of 18 mobile app developers will join the PayPal technology team to help build creative and simple ways for consumers to use the PayPal digital wallet, Barrese says. He adds that the Duff Research team has built more than 40 apps and has won four Best of the Consumer Electronics Show awards and two technical Emmy awards. Duff Research clients include Adidas AG and TiVo Inc.

“PayPal is giving our team the opportunity to transform an industry and enhance people’s daily lives with technology,” Duff Research said in a statement. “They’ve built the industry’s leading online payments platform, and our entire team is excited by the opportunity to work with the amazing group of technologists already at PayPal. As entrepreneurs, working in a culture of innovation and making an impact on the future of shopping and payments with millions of customers is what we found most attractive at PayPal.”

PayPal in January said that 23 national retailers now accept PayPal payments inside their stores. PayPal says consumers can pay via payment terminals inside some 18,000 retail locations. Consumers pay by either entering the same log-in and password they use for PayPal online or by swiping one of three payment cards co-branded by PayPal and MasterCard. Retail chains accepting PayPal include Abercrombie & Fitch Co., Aéropostale Inc., Barnes & Noble, Famous Footwear, J.C. Penney Co. Inc. and RadioShack Corp.