Senior Software Developer - Cards

BUILD SOMETHING PEOPLE LOVE Wealthsimple is Canada’s leading financial innovator. The company offers a full suite of simple, sophisticated financial products across managed investing, do-it-yourself trading, cryptocurrency, tax filing, spending and saving. Wealthsimple currently serves more than 4 million Canadians and holds over $155 billion in assets under administration. The company was founded in 2014 by a team of financial experts and technology entrepreneurs, and is headquartered in Toronto, Canada. We're proud of what we've built — and we're just getting started. Read our Culture Manual https://www.wealthsimple.com/en-ca/culture and learn more about how we work https://www.wealthsimple.com/en-ca/careers. ABOUT THE ROLE As a Senior Software Developer on the Cards team, you'll own meaningful slices of the card stack end to end — from card issuance and authorization through transaction processing, disputes, rewards, and card lifecycle management. This is not a features-on-top-of-a-BaaS role. We're building card infrastructure in-house, and the person we hire will be able to say they built it. You'll bring strong technical judgment, a bias toward action, and a deep sense of ownership. You'll work closely with product managers, designers, and engineers to turn complex, high-stakes problems into simple, reliable experiences for millions of Canadians. WHAT YOU'LL DO - Shape and own greenfield work in a space that's still early for Wealthsimple — our card program is still in its early years and there's significant greenfield building ahead; if you've built something from scratch before, that experience will go far here - Own complex, end-to-end projects across the card stack — from technical design through implementation, launch, and iteration - Build and improve the backend systems that power our card products, with a focus on reliability, performance, and correctness - Work on core card infrastructure: card issuance, tokenization, authorization flows, BIN management, transaction processing, card lifecycle management, and dispute infrastructure - Make thoughtful architectural decisions and help the team balance speed, quality, and scale — influence what we build, how we build it, and where we go next - Partner closely with Product and Design to clarify goals, surface trade-offs, and deliver outcomes — not just features - Build with the reliability and observability standards that card journeys demand — a declined tap or a poorly handled dispute is felt immediately by our members - Leverage AI-centric workflows to ship faster and safer — we invest heavily in AI tooling and expect senior engineers to push the frontier of how we use these tools - Raise the technical bar through design reviews, code reviews, documentation, pairing, and mentorship - Help create a team culture where people communicate clearly, learn quickly, and take ownership together WHAT YOU BRING - 5+ years of professional software engineering experience and a track record of shipping production-grade systems that real users depend on - Experience building and owning backend systems in a payments, card, or financial services environment — ideally with direct exposure to card issuance, authorization, payment rails, or card lifecycle management - Strong backend engineering fundamentals — you understand how money moves, how systems fail, and how to build for correctness at scale - A maker-owner mindset: you're looking for a place to plant a flag, take ownership of a growing domain, and shape it over time — motivated by building the best card program in Canada, not just shipping the next ticket - Comfort with ambiguity and greenfield work — you've built something from 0→1 before and thrive in an environment where not everything is defined yet - An AI-first development workflow that doesn't compromise on rigour — you've moved beyond AI as autocomplete into genuinely agentic workflows, and bring the engineering judgment to know when the model is wrong - Product judgm…