Sr. Staff AI/ML Engineer

About Gusto At Gusto, we're on a mission to grow the small business economy. We handle the hard stuff — payroll, health insurance, 401(k)s, and HR — so owners can focus on their craft and their customers. With teams in Denver, San Francisco, and New York, we support more than 500,000 small businesses nationwide and are building a workplace that reflects the people we serve. All full-time employees receive competitive base pay, benefits, and equity (RSUs) — because everyone who helps build Gusto should share in its success. Offer amounts are determined by role, level, and location. Learn more about our Total Rewards philosophy . AI is a fundamental part of how work gets done at Gusto. We expect all team members to actively engage with AI tools relevant to their role and grow their fluency as the technology evolves. AI experience requirements vary by role and will be assessed during the interview process. About the Role: You'll design, build, and scale the AI platform that empowers Gusto's internal teams to build intelligent agents and deliver customer value. This includes developing core platform capabilities — agent orchestration, RAG infrastructure, eval tooling, model serving, prompt management, observability, and safety guardrails — that enable product teams to rapidly build, test, and ship AI-powered experiences. You'll own the full lifecycle from problem framing to production deployment, ensuring the platform is reliable, performant, and easy to adopt. As a Staff MLE, you'll also shape technical standards, drive architectural decisions, and mentor engineers across the organization. About the Team: You'll join the CoreX AI Platform team, responsible for building the foundational AI infrastructure that Gusto's internal app teams rely on to create and ship intelligent agents. We're a small, high-impact group of ML engineers and platform builders working closely with Product Engineers, PMs, and Designers across the company. We move fast, prototype boldly, and focus on making it easy for any team a What you'll do day-to-day: Design and build scalable platform services — agent orchestration, RAG pipelines, eval frameworks, model serving — that internal teams use to ship AI-powered products. Lead technical strategy and architecture for the AI platform, including model lifecycle, observability, safety guardrails, and evaluation infrastructure. Collaborate cross-functionally with app teams, PMs, and Designers to understand their AI needs and deliver platform capabilities that unblock them. Build, harden, and operate shared infrastructure that powers intelligent agents across Gusto (e.g., retrieval, routing, prompt management, content selection). Stay current with AI/ML research; rapidly prototype and productionize new techniques that strengthen the platform. Establish robust practices for validation, deployment, monitoring, and ongoing performance management of platform services and the agents built on them. Communicate technical strategy, tradeoffs, and impact clearly to executives and non-technical partners. Mentor engineers across teams, raising the bar on AI/ML best practices and fostering a culture of pragmatic innovation. Here’s what we’re looking for 12+ years building and deploying end-to-end AI/ML systems, with experience designing platform-level infrastructure that other engineering teams build on. Deep expertise in one or more areas: LLMs, NLP, retrieval/RAG, agent orchestration, deep learning, or reinforcement learning. Hands-on experience building LLM-based applications and agentic workflows — including prompt engineering, retrieval design, evaluation, and production deployment. Proficiency with modern ML frameworks (PyTorch, TensorFlow, Hugging Face) and cloud platforms (GCP, AWS, or Azure). Strong Python skills and sound software engineering fundamentals — testing, code review, CI/CD, reliability, and API design. Proven track record shipping impactful AI/ML projects to production, ideally in a platform or infrastruc