Sr Staff Engineer - Full Stack

Senior Staff Engineer — Full-Stack, Solution Architecture

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.

Must-haves — technical:

• 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 ven 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.”

Must-haves — delivery & ownership

• 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 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