BMO Harris is adding cashless ATM access to 750 machines, enabling customers to withdraw cash using a smartphone application instead of a plastic card.

The Chicago-based bank claims this technology, which uses QR codes to communicate with its ATMs, gives it the largest cardless network of ATMs in the country. The company, a unit of BMO Financial Group, plans to enable cashless access for 150 more machines in June. It has about 1,300 machines in the U.S.

"Smartphones are quickly becoming the singular device that people use to help manage their life," Connie Stefankiewicz, BMO's head of North American channel strategy and solutions, said in a March 16 press release.

Other financial institutions that allow cardless ATM access include Wintrust Financial, a holding company for 15 banks that uses cardless ATM technology from FIS; and Diebold Federal Credit Union, which uses technology developed by Diebold and Paydiant. SunTrust, City National Bank, RBS and Natwest also allow customers to extract cash from an ATM using a mobile app, and machines such as Fexco's Cashebo are designed with this type of interaction in mind.

BMO's mobile banking app will allow customers to search for the ATMs that support the new card-less transactions, BMO says it has about 750 of its approximately 1,300 ATMs ready for card-less transactions now. The bank expects about 150 more will come online in June.