Senior Staff Engineer — Full-Stack
About the role
Our client is building an AI-centric engineering platform where brands operate as self-reliant, B2B-style customers. You will own product features end-to-end across the full stack — leveraging AI agents to multiply delivery throughput — while architecting robust, highly-available systems on a stable, brand-agnostic platform.
This is a full-time IN-OFFICE position in Toronto.
What you will do:
• Own delivery of product features end-to-end: design, build, verify against acceptance criteria, and ship to production.
• Build and operate 3rd-party and B2B integrations on the platform, delivering brand- and customer-specific features on top of a shared core.
• Use AI coding agents and automated verification to accelerate delivery, working within engineering quality gates and independent review.
• Set technical patterns and unblock yourself and others across a fast-moving, multi-workstream environment.
Technical must have:
• Full-stack, production-grade. Senior/staff experience building software end-to-end: .NET / C# REST APIs and Next.js / React front-ends with server-side rendering and real-time streaming (Server-Sent Events).
• Architecture at scale. Proven design and operation of highly-available, high-throughput systems.
• Data. Hands-on with MongoDB, Redis (sessions, caching, sorted-set/leaderboard patterns) and PostgreSQL; chooses the right store per workload.
• Event-driven systems. Building producers/consumers on an event hub / Apache Kafka; event-schema design and real-time aggregations.
• 3rd-party and B2B integrations. Designing and delivering integrations against external and game-provider APIs, and building brand-/customer-specific capabilities on a stable, brand-agnostic platform.
• API security.



OAuth-based auth, request signing (HMAC), idempotency, replay protection, and audit logging.
• AI-assisted delivery. Demonstrated use of AI coding agents/tooling to multiply throughput, and fluency working within automated verification (testing against acceptance criteria, regression, edge cases).
• Hands-on production monitoring. Operating production monitoring and issue triage (Sentry or equivalent); treats observability and CI/CD as part of “done.”
Delivery & Ownership - must have:
• Proven track record of delivering robust solutions within tight, fixed timeframes — quality and speed together, not one at the expense of the other.
• Handles competing priorities across multiple workstreams without dropping commitments.
• End-to-end ownership of deliverables, from an ambiguous problem statement through to production.
• A can-do operator who embraces uncertainty and figures things out as they go — self-sufficient, decisive with incomplete information, and escalates judiciously rather than by default.
Benefits
• Exposure to cutting-edge AI and automation technology that is actively transforming how marketing and operations are run at scale
• Genuinely interesting projects with modern tooling, and the freedom to bring your own ideas to the table
• A collaborative, high-performance culture where ambition, accountability, and innovation are valued and rewarded
• Clear paths for development, progression, and advancement as the business scales
• A market-competitive salary plus discretionary bonus
• Comprehensive health benefits, including extended healthcare, dental, and vision coverage.
• On-site leisure facilities to switch off and recharge during the day.
• Fantastic company events
• On-site leisure facilities and on-site parking

📌 Sr Staff Engineer, Solution Architect - Full Stack (Toronto)
🏢 CareerBeacon
📍 Toronto