Fiserv (FISV) has added another customer for its online billing platform.

The fintech company said Monday that Union Bank will use Fiserv's CheckFree RXP system to automate delivery of bills and payments for the $97 billion-asset institution's customers.

Fiserv's platform provides for the delivery of bills from roughly 500 businesses, including utilities, mobile phone and credit card companies, while allowing banks to customize the display, according to the company.

Customers of San Francisco-based Union Bank will be able to use CheckFree online and via their smartphones to view and pay bills electronically.

"Usability and accessibility are the keys to driving bill payment adoption, and Union Bank will deliver both with the integration of CheckFree RXP into their online and mobile banking services," Rahul Gupta, Fiserv's group president for digital payment solutions, said in a press release.