Senior Software Developer, Book of Record (Core Balances)

Job description

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 We're growing the Core Balances team and looking for a Senior Software Developer to take real ownership of the services at the heart of how Wealthsimple tracks client money. You'll join a small, high-trust group of senior engineers and own meaningful scope from early on - designing and building the backend systems that track balances, reserve assets, and record financial activity in real time. It's backend-heavy, consequential work: these services sit on the critical path for nearly every product at Wealthsimple, and the rest of the company trusts them to be both fast and correct. You'll partner closely with Product and neighbouring engineering teams to turn complex financial logic into experiences that feel simple to the people relying on them. IN THIS ROLE, YOU'LL HAVE THE OPPORTUNITY TO: - Design, build, and operate the backend services that power real-time balances, reservations, and financial activity - the systems the rest of Wealthsimple trusts to be correct. - Own meaningful scope end-to-end, from technical design through to running your work reliably in production. - Solve genuinely hard problems around real-time correctness, low latency, and high availability: write paths that can't be slow, event consumers that can't fall behind, and database contention that shows up exactly when volume peaks. Keeping all of it dependable through market open and other busy moments is part of the job. - Evolve our architecture in place. These systems have grown alongside Wealthsimple itself, from a single product to an entire financial ecosystem, and a big part of the work ahead is reshaping them to fit the company we are now - consolidating overlapping services and data models, establishing a single entry point for financial activity, isolating failure domains so one slow calculation can't degrade everything around it, and making recovery and backfill fast and safe. Doing this on live financial systems, without downtime and without ever showing a client the wrong number, is the interesting part. - Raise the bar on quality and operational excellence through thoughtful design, code review, and a healthy sense of production ownership. - Mentor and grow the engineers around you - through pairing, code review, and in-the-moment feedback - and learn just as much from them in return. - Use AI-assisted tooling to ship faster and more safely. We treat building with AI as part of how we work, and we're always figuring out how to do it well. WHAT YOU BRING: - 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. - Solid experience building services that are highly available and low-latency - and the instincts that come from having kept one running under real load. - 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. - You take production ownership seriously and stay calm and methodical when things go wrong. - 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. - 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. - 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. - 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. - Enthusiasm for AI-assisted development, and interest in helping shape what excellent, rigorous AI-assisted engineering looks like on our team. NICE TO HAVE: - Experience in fintech, banking, trading, or another regulated, high-stakes domain - ideally at a fast-moving, high-growth company. - Familiarity with ledgers, reconciliation, or financial-correctness problems. - Experience with event-driven architecture and stream processing (Kafka, Flink, or similar), and the patterns that keep it correct - idempotency, ordering, transactional outboxes. - 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 carrying out significant migrations on live, high-traffic systems. WHO YOU ARE: - You take ownership end-to-end - from the design to the code to making sure it holds up in production. - You're comfortable with ambiguity and do your best work in a domain where the problems are consequential and rarely perfectly clean. - 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. - 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. 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. WHY WEALTHSIMPLE? 🌸 Top-tier health benefits and life insurance 📈 Long-term group savings with employer match, through Wealthsimple for Business 🌴 20 vacation days, 4 wellness days, and unlimited sick and mental health days per year ✈️ 90 days away: work outside Canada for up to 90 days per year 👥 Employee resource groups, including Rainbow (2SLGBTQ), Women of WS, and Black at WS 🌎 We are a hybrid team with over 1,500 employees across North America. The people are one of the best parts of working here: you'll collaborate with incredibly talented, curious, and driven teammates who are deeply committed to doing great work. ICYMI Technology & Innovation at Wealthsimple: We move quickly and build thoughtfully. That means we're always looking for better ways to work — whether that's new tools, AI, or rethinking how we approach a problem. We don't expect you to have all the answers, but we do expect curiosity and a willingness to evolve alongside the products we're building. Inclusion Statement: We're building products for a diverse world, and we need a diverse team to do it well. We strongly encourage applications from everyone, regardless of race, religion, colour, national origin, gender, sexual orientation, age, marital status, or disability status. Accessibility Statement: We're committed to an accessible hiring experience. If you need any accommodations throughout the interview process, please let us know — we'll work with you to make sure you have what you need. We also welcome any feedback on how we can better accommodate candidates with accessibility needs. AI in Hiring: We may use artificial intelligence (AI) tools to support parts of our hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our team but don't replace human judgment – all final hiring decisions are made by people. If you have questions about how your data is used, reach out to us.