Senior Software Engineer, AI

Justworks•Toronto, ON

9d•CA$188,000 - CA$242,000•Hybrid

About The Position

You will join a small, highly autonomous cross-functional team to build AI agents that fundamentally transform how operations work at scale. Instead of writing bespoke software for every workflow, we are developing an agent platform that can read operational knowledge, reason about it in context, and execute tasks end-to-end. This approach allows us to scale complexity through knowledge and reasoning, rather than simply through code. This is an opportunity to join a foundational team, which currently consists of fewer than five engineers. The work spans critical areas including LLM-powered agent design, robust backend service architecture, tool and integration development, and sophisticated knowledge infrastructure. We are seeking a Senior Software Engineer with a strong passion for building AI-native systems in a product environment. The ideal candidate will be able to take ownership of large segments of the technology stack, make pragmatic technical decisions in ambiguous and emerging territory, and consistently ship high-quality, production-ready systems that our users rely on every day.

Requirements

5+ years of backend engineering experience building and operating production systems
Hands-on experience with LLMs and AI agents (orchestration, RAG, tool/function calling, or similar)
Strong API design and system integration skills
Product-minded: questions requirements and contributes to product decisions, not just execution
Proven ownership of complex projects in ambiguous, early-stage environments

Responsibilities

Design, build, and own core components of the agent platform, from the orchestration layer to the tool integrations connecting it to internal systems.
Build and evolve the capabilities layer: APIs, data access patterns, and service integrations for agents to execute operational workflows.
Architect the knowledge and memory infrastructure, allowing agents to retrieve the data and act across our systems.
Design and implement the trust and safety framework, including audit trails, human-in-the-loop controls, and guardrails for safe and auditable AI-driven operations.
Contribute to agent evaluation and testing infrastructure, defining how we measure accuracy, reliability, and regression across agent behaviors.
Partner directly with Operations to understand workflows, identify automation opportunities, and translate process knowledge into agent capabilities.
Mentor other engineers on the team as it grows.