Senior Software Engineer, Applied AI (Toronto)

At Justworks, you’ll enjoy a welcoming and casual environment, great benefits, wellness program offerings, company retreats, and the ability to interact with and learn from leaders in the startup community. We work hard and care about our most prized asset - our people. We’re helping businesses get off the ground by enabling them to focus on running their business. We solve HR issues. We’re data-driven and never stop iterating.

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.

• 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.

• 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

Golang, Ruby on Rails, Javascript, Java, C#, Python, VueJS, MySQL, Kafka, AWS, Git, Memcache, Redis, ElasticSearch, Docker, Terraform, Kubernetes, CircleCI, DataDog

The base wage range for this position based in our Toronto office is targeted at $188,000.00 to $242,000.00 CAD per year. Actual compensation is based on multiple factors that are unique to each candidate, including and not limited to skill set, level of relevant experience, and specific work location. For more information about Justworks’ Total Reward Philosophy, including all of the perks and benefits we are proud to offer our team members, please visit Total Rewards @ Justworks.

Justworks is committed to maintaining a workplace where diversity of identity, culture, and life experience is the norm and is celebrated authentically and respected consistently. We’re proud to be an equal opportunity employer open to all qualified applicants regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital or familial status, disability, pregnancy, gender identity or expression, veteran status, genetic information, or any other legally protected status.