By Kylie Madry

MEXICO CITY (Reuters) - Spanish banking giant Santander started rolling out its digital Openbank in Mexico on Tuesday, including a website and smartphone app.

WHY IT'S IMPORTANT

So-called fintechs have taken Mexico by storm in recent years, gobbling up market share as unbanked Mexicans go online and traditional bank clients reject what they view as poor service.

Openbank adds a new, strictly digital option to Santander, which already offers app-based services and online banking. Clients previously registered for the waiting list will be the first to join Openbank.

CONTEXT

Openbank already operates in Spain, Germany, Portugal and the Netherlands, and is the largest digital bank in Europe by deposits, Santander said.

KEY QUOTE

Mexico has huge potential for a digital bank, said Openbank head Petri Nikkila in a statement. "We hope to become a reference point for Mexican clients who want such competitive products."

BY THE NUMBERS

Openbank is offering a savings account with a 12.5% annual return in Mexico, in line with other digital banks in the country such as Nubank.

WHAT'S NEXT

Openbank will roll out new products and services for its clients in Mexico in the coming months, it said, without elaborating.

(Reporting by Kylie Madry; Editing by David Alire Garcia and Richard Chang)