Senior AI Platform Engineer — LLM Agents

Justworks; International Falls (MN); Hybrid; USD 120,000 - 180,000; Full time

Job summary

Justworks is building an AI-native agent platform to transform operations at scale. You will join a small, autonomous team delivering end-to-end workflows through a knowledge-driven architecture, integrating tools and internal systems with a focus on reliability and scale.

The role requires owning large parts of the stack, making pragmatic technical decisions in emerging territory, and shipping production-ready systems used by customers daily.

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

System integration

Tools

Golang

Ruby on Rails

JavaScript

Python

Docker

Kubernetes

Job description

Justworks is building an AI-native agent platform to transform operations at scale. You will join a small, autonomous team delivering end-to-end workflows through a knowledge-driven architecture, integrating tools and internal systems with a focus on reliability and scale.

The role requires owning large parts of the stack, making pragmatic technical decisions in emerging territory, and shipping production-ready systems used by customers daily.