Senior Full Stack Developer, Contract (4)

Role

Senior Full Stack Developer (Contract) — 4 positions. Contract through December 24, 2026. Work in a hybrid model with required in-office collaboration in Toronto 2 days per week. The role combines traditional full-stack responsibilities (React, Node.js, SSR, API design) with AI-focused engineering: building agentic workflows, LLM integrations, prompt engineering, and automated evaluation pipelines.

Key Responsibilities

Core Engineering

• Optimize website and application performance for speed and efficiency.
• Design and develop APIs (REST and GraphQL) and end-to-end web applications (front end and back end).
• Work across the full web development lifecycle, including SSR applications.
• Build secure services with attention to OAuth2/OIDC, API key management, and access auditing.

AI Engineering

• Build and maintain automated evaluation pipelines (LLM-as-judge scoring, regression tests, golden datasets) to measure prompt/model changes.
• Define strict typed input/output contracts (TypeScript interfaces, JSON Schema) for tools and agent skills; ensure structured errors and unambiguous outputs.
• Own prompt engineering lifecycle for assigned tools and skills: version-controlled templates, parametric input injection, and system/user role separation.
• Implement, test, and document MCP-compatible API integrations, especially GraphQL/Apollo and developer-portal tooling; participate in rollout readiness (SLOs, support docs).
• Build agentic workflows: multi-step tool chains, state-machine or orchestration frameworks with deterministic routing and graceful failure handling.

Requirements

• Available to collaborate in the Toronto office 2 days per week.
• 5+ years working with modern frameworks and languages, specifically React and Node.js.
• Experience with SSR applications.
• Experience with GraphQL and Apollo; building or integrating REST/GraphQL APIs and managing API contracts and versioning.
• Familiarity with OAuth2/OIDC, API key management, and access audit trail patterns.
• Familiarity with SLO definition and observability practices (logs, metrics, distributed traces) for production services.
• Hands-on experience with LLM structured output patterns (function/tool calling).
• Familiarity with LLM evaluation approaches: golden test sets, LLM-as-judge pipelines, and prompt regression testing; ability to quantify output quality with measurable metrics.
• Experience building agentic workflows or orchestration frameworks (e.g., LangGraph, LangChain, AutoGen, or custom) with deterministic routing and failure handling.

Nice to Have

• Experience defining and rolling out engineering standards (coding conventions, PR workflows, testing mandates, API contracts).
• Experience managing or mentoring engineers, including performance and career conversations.
• Track record driving AI tool adoption across teams (onboarding, guidance, culture).
• Familiarity with AWS and Docker.
• Experience with Styled Components.
• Experience with prompt caching, semantic routing, or output memorization strategies.
• Ability to instrument LLM calls with structured traces (input, output, latency, token counts, invoked tool calls) using frameworks like LangSmith or OpenTelemetry; define SLOs for agent task success.

Contract & Location

• Contract role through December 24, 2026.
• Hybrid: Toronto office presence required 2 days per week.
• Multiple openings (4 positions).

What the Company Offers (selected)

• Hybrid work with in-office collaboration in Toronto (2 days/week).
• Professional development opportunities: conferences, online courses, Lunch n’ Learns.
• Access to Kyu Collective resources, training, and offices.
• Social and team events (regular social committee activities).
• Dedicated DEI initiatives and an inclusive, accessible workplace.