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Gusto is building Otto, an AI agent that helps customer support advocates solve complex payroll, benefits, and compliance problems for small businesses. As a Staff Software Engineer on the Gustie Assist platform team, you'll own a meaningful slice of Otto end-to-end, spanning the LLM agent runtime, tool/action layer that enables safe autonomous actions, Rails/GraphQL backend, advocate-facing frontend, and evaluation systems that ensure reliability as the agent touches live customer accounts.
Day-to-day responsibilities include designing and building across the Otto platform with a focus on expanding what the agent can safely do through autonomous, tool-using actions with human-in-the-loop approval. You'll build evaluation and observability systems (LLM-as-judge, deterministic scorers, offline gates, production monitoring) that enable weekly agent updates without regressing correctness. You'll work directly with LLMs on prompting, tool design, retrieval, and feedback loops that turn real advocate interactions into improved capabilities. You'll partner closely with Product, Data, Design, and CX teams to translate pain points into shipped features, and mentor engineers on building agentic systems responsibly at scale.
You'll typically have 8+ years of software engineering experience owning systems end-to-end, with proven track record shipping LLM-powered or agentic systems in production (tool-calling, retrieval, evals). Strong full-stack capability is essential—you move fluidly between backend services, LLM runtimes, and customer-facing product. You've owned multi-quarter projects with measurable user impact at scale and demonstrate sound judgment about safety and blast radius when software takes real actions on real accounts. Experience with agent frameworks, evals/LLM-as-judge, Ruby on Rails, JavaScript/React, GraphQL, and federated backends is valuable. Gusto operates hybrid with 2-3 days per week in-office at Denver, San Francisco, or New York locations.
