Senior Full Stack Engineer, Client Platform

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Full Stack Engineer, Client Platform based in Canada. This is a senior full-stack engineering role focused on enabling product teams to build and deliver high-quality digital experiences efficiently. You will work across shared front-end libraries, design systems, developer tooling, and a server-driven UI platform. The role combines React and TypeScript development with backend GraphQL engineering and API design. You will help shape the contracts that power web and mobile experiences while ensuring performance, accessibility, observability, and reliability. The position involves solving complex technical challenges within a large monorepo and distributed service environment. You will also contribute to architecture, technical standards, testing practices, and mentoring in a collaborative Agile team. Accountabilities: - Design and evolve GraphQL schemas within a federated graph, including server-driven UI contracts consumed by web and mobile clients. - Manage GraphQL schemas as versioned contracts, identifying breaking changes, coordinating migrations across client teams, and keeping generated client models synchronized. - Develop, scale, and optimize GraphQL APIs, RPC endpoints, and SQL queries supporting digital client experiences. - Build front-end applications and shared component libraries using React and TypeScript, with a strong focus on performance and accessibility. - Partner with product and design teams to architect and deliver customer-facing features end-to-end. - Use observability tools to diagnose production issues, improve user experiences, and establish effective monitoring and alerting through Datadog. - Identify technical debt, production bottlenecks, scalability risks, and opportunities to improve code quality and platform performance. - Contribute to system design, architecture, feature delivery, and technical standards within a collaborative Agile environment. - Develop comprehensive automated tests for new features and bug fixes, working with QA to strengthen testing pipelines and CI/CD workflows.

- Mentor engineers through code reviews, pairing, documentation, and knowledge sharing. - Incorporate agentic development tools such as Claude Code into daily engineering workflows while maintaining strong quality standards. Requirements: - At least 5 years of professional software engineering experience. - Strong JavaScript, TypeScript, and React skills, combined with solid UX instincts. - At least 2 years of experience designing and evolving GraphQL schemas for product surfaces used across multiple clients, including iOS, Android, and web. - Strong knowledge of HTML, CSS, and browser technologies, including the DOM, events, and platform APIs. - Solid computer science fundamentals, including data structures, algorithms, distributed systems, and software design. - Experience working with production systems at scale, including load testing, tracing, performance analysis, and optimization. - Experience investigating and resolving production performance regressions, including CPU hotspots and latency issues in high-throughput services. - Experience participating in on-call rotations and owning production release cycles end-to-end. - Strong focus on clean architecture, maintainable code, and software craftsmanship. - Excellent written and verbal communication skills, with experience producing technical specifications, runbooks, and cross-team design documentation. - Experience developing APIs with Node. js, Bun, or another server framework such as Phoenix, Ruby on Rails, FastAPI, or Laravel. - Experience building multi-client or white-label platforms, including geo-based routing and per-brand configuration. - Experience with Kubernetes and operating services in containerized environments.