Senior Software Developer (Book of Record (Core Balances))

Join Wealthsimple, a fast-growing fintech company, as a Senior Software Developer in the Core Balances team. You'll design and build backend systems that track balances, reserve assets, and record financial activity in real-time. This role involves solving complex problems around real-time correctness, low latency, and high availability, while also mentoring and growing the engineers around you. Enjoy a range of benefits, including retirement savings matching, company equity, paid parental leave, and top-tier health benefits.

• Concevoir, construire et exploiter les services backend qui alimentent les soldes en temps réel, les réservations et l'activité financière.
• Posséder une portée significative de bout en bout, de la conception technique à l'exécution fiable de votre travail en production.
• Résoudre des problèmes difficiles liés à la correction en temps réel, à la faible latence et à la haute disponibilité.
• We work primarily in Kotlin on the JVM, with Kafka and GraphQL in the mix - strong Java experience translates well, and deep experience in a comparable stack matters more than an exact match. We'll help you ramp on ours
• Comfort working in a mature codebase - you can find your footing in systems with history, and you improve them incrementally rather than waiting for a clean slate
• Enthusiasm for AI-assisted development, and interest in helping shape what excellent, rigorous AI-assisted engineering looks like on our team
• Several years (5+) of professional software engineering experience, with a track record of building and operating critical production systems that people or businesses depend on
• Strong backend engineering skills and sound judgment about system design, reliability, and trade-offs
• Curiosity about the "why" behind the systems - not just the code, but the financial reality it represents and the clients on the other side of it
• You take production ownership seriously and stay calm and methodical when things go wrong
• Solid experience building services that are highly available and low-latency - and the instincts that come from having kept one running under real load
• Clear, steady communication. You work well with Product and other engineering teams, share context early, and ask questions before you're stuck rather than disappearing down a hole
• Strong software quality habits: you write well-tested, maintainable and observable code. You make the codebase and the people around you better through your reviews
• You're comfortable with ambiguity and do your best work in a domain where the problems are consequential and rarely perfectly clean
• You're detail-oriented without losing the bigger picture - you care deeply about correctness, and about the experience for the client on the other side of it
• You're collaborative and generous by default: you share what you know, invest in the people around you, and help the whole team get better
• You're curious and always learning - open to new ideas, new perspectives, and new ways of working
• You take ownership end-to-end - from the design to the code to making sure it holds up in production
• You're pragmatic about legacy: you can tell the difference between complexity that's load-bearing and complexity that's just old, and you know how to unwind the second kind safely
• If this sounds like the kind of work you want to do, we'd love to hear from you - even if you don't tick every single box above. Depth, judgment, and a genuine interest in the problem count for a lot
• Experience carrying out significant migrations on live, high-traffic systems
• Experience with GraphQL APIs, Apollo Federation, or Kubernetes
• Depth in relational database performance at scale - Postgres, connection pooling, replication, and diagnosing contention under load
• Experience with event-driven architecture and stream processing (Kafka, Flink, or similar), and the patterns that keep it correct - idempotency, ordering, transactional outboxes
• Familiarity with ledgers, reconciliation, or financial-correctness problems
• Experience in fintech, banking, trading, or another regulated, high-stakes domain - ideally at a fast-moving, high-growth company