Senior Full Stack Engineer

About the Role

We're looking for a Senior Full Stack Engineer to own the product surface of our end to end: our web app (Next.js), our mobile app (Expo / React Native), and the TypeScript backend-for-frontend that serves both. You'll be the most senior product engineer on the team.

This is an ownership role. You'll set the bar for product quality, decide how features are structured across web, mobile, and BFF, and be the person the team looks to when a flow is broken and nobody knows why. Over time we'd like you to become the owner of our mobile app - in addition to the rest of the stack, not instead of it. You'll ship the user-facing side of things that don't exist yet in Canada: a chequing account, a card we issue, instant payouts.

What You'll Be Doing

• Own the product surface across web, mobile, and the BFF - architecture, quality bar, observability, and roadmap
• Lead the design of new product flows for chequing, card issuance, and instant payouts across every client
• Own onboarding and activation end to end - the biggest lever in the company
• Make the BFF the single reliable contract for web and mobile: strict schemas, versioning, and backward compatibility for app builds in the wild
• Grow into owning mobile: release process, OTA updates, store submissions, and the health of the app
• Set the technical bar: review architecture, write the patterns others follow, and push back when something isn't right
• Mentor product engineers through reviews and pairing
• Work directly with the CTO and product on what we build next and in what order

What Senior Means Here

• You make trade-off calls without waiting to be told, and you're right most of the time
• You surface problems early and specifically - before they hit users
• You disagree openly, then commit fully
• You multiply the team - patterns, reviews, mentoring - rather than only shipping your own work
• You own outcomes, not tasks. If your domain is broken, that's yours to fix, not someone else's to notice

Who We're Looking For

• Substantial experience shipping production TypeScript across the stack - React/Next.js at scale, plus a real backend (Node - Hono, NestJS, Express - with a proper data layer)
• React Native / Expo in production, or a strong desire to own it and the judgment to get there fast
• You've owned a product surface before - not "worked on," owned - through launches, incidents, and redesigns
• You care about correctness in ways most product engineers don't: schemas, auth boundaries, idempotent mutations, money shown right
• You have taste, and you can explain it
• You already build with AI coding tools every day and have strong opinions about where they fail
• You've been early somewhere and liked it - you're comfortable making decisions with 70% of the information and revisiting them when the picture changes
• You communicate clearly in writing and don't need a manager to tell you what matters

Bonus Points

• Fintech or another domain where a wrong number is a real problem
• Design-system ownership, accessibility, or i18n (we ship in English and French)
• Datadog RUM or similar frontend observability