Originally developed by Starling's own in-house tech team, Engine is an API-based, cloud-native platform for managing the UK bank. Starling started providing Engine to other lenders in 2022, pledging to assist them in swiftly introducing new digital services or swapping out antiquated infrastructure.

Only two clients—Salt Bank in Romania and AMP Bank in Australia—have been acquired by the platform thus far. Chrysalis, an investment trust, is Starling's second-largest stakeholder and anticipates that Engine will provide a sizable amount of income.

Engine has "a strong pipeline," according to Chrysalis co-manager Richard Watts, who tells the Financial Times that the company may have 40–50 clients in a few years, "which would equate to a revenue opportunity of many hundreds of millions of pounds per annum."

The rival bank may "see a valuation approaching £10 billion" as a result of this.

Jupiter Asset Management sold 6% of Starling last year for £1.5 billion, which represents a billion-pound discount to the bank's 2022 internal fundraising estimate.

Since opting against entering Europe through an Irish banking licence, Starling has been placing bets on Engine to spearhead its global development. It struck a contract in December with the world's largest professional services firm, PwC, which would make Engine available to its clients globally.

According to Watts, "We’ve been pushing for Engine to be developed to drive Starling’s growth, as this proposition opens up a global market for bank infrastructure."