Banks Beware, Outsiders Are Cracking the Code for Finance

An employee walks past a sign at Shopify's headquarters in Ottawa, Ontario, Canada, on Oct. 22, 2018. Chris Wattie/Reuters

LONDON—Anyone can be a banker these days, you just need the right code.

Global brands from Mercedes and Amazon to IKEA and Walmart are cutting out the traditional financial middleman and plugging in software from tech startups to offer customers everything from banking and credit to insurance.