Senior Software Developer - Cards Team

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 judgment: you care about the member problem, can simplify complexity, and know when to iterate versus when to invest for the long term
• The ability to navigate ambiguity, define a path forward, and bring others along through clear written and verbal communication
• Technical leadership and mentorship instincts — you raise the bar through your code, your reviews, your design documents, and the way you support your teammates
• A collaborative, low-ego approach to engineering and a willingness to give and receive candid feedback

Nice to have experience

• Experience working directly with card networks or card processors — on either side of the integration
• Experience building card infrastructure in-house rather than on top of a BaaS platform
• Ruby on Rails or experience in a comparable backend language — Ruby is helpful but not a requirement; depth and willingness to ramp matter more
• React and/or React Native experience
• Experience in a fast-moving environment where engineers have broad ownership and meaningful influence over product decisions