Senior Software Engineer - Mercury Command

<p>In 1965, an engineer in Scotland was given a mundane task with a tricky problem to it - banks wanted to close on Saturdays and still serve customers, but they didn’t know how to solve the authentication of the right user. James Goodfellow, working at Smiths Industries, uncovered the insights that you needed something you have (a card) and something you know (a PIN). Because someone told him they could only remember 4 digits instead of his proposed 6, today over 3 million ATMs use a card+4 digit PIN over 60 years later. </p> <p>Like the ATM, Mercury is building technology that pushes forward financial interfaces for the long term. Command is Mercury's LLM-powered financial assistant, launched to all customers in June 2026. It lets users understand their finances and take action in plain language, from asking about cash flow to sending payments, issuing cards, and managing invoices. With the product now in customers' hands, the work is to evolve it,