Senior AI Software Engineer - Scalable Agent Platform

Justworks, Inc.; Toronto; Hybrid; CAD 188,000 - 242,000; Full time

Benefits offered by this job

Great benefits

Wellness program

Company retreats

Job summary

Justworks, Inc. is seeking a Senior Software Engineer to join a small, autonomous team building AI-native systems that scale operations. You will own large sections of the technology stack, drive pragmatic decisions in evolving space, and ship production-ready systems relied on daily.

You will contribute to agent design, backend architecture, and knowledge infrastructure while mentoring peers. The role blends hands-on development with strategic product thinking in a fast-paced, early-stage

Qualifications

• 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.

Skills

Backend engineering

LLMs & AI agents

API design

Product-minded

Ownership of complex projects

Tools

Production systems

Job description

Justworks, Inc. is seeking a Senior Software Engineer to join a small, autonomous team building AI-native systems that scale operations. You will own large sections of the technology stack, drive pragmatic decisions in evolving space, and ship production-ready systems relied on daily.

You will contribute to agent design, backend architecture, and knowledge infrastructure while mentoring peers. The role blends hands-on development with strategic product thinking in a fast-paced, early-stage