Staff/Principal AI/ML Engineer

What We’re Looking for

Zus is hiring a Staff/Principal AI/ML Engineer to define how LLMs and AI agents power our products and the AI platform underneath them. You'll be one of the most seasoned AI/ML voices in the building, with real ownership of architecture, tooling and roadmap.

• Zus aggregates clinical data from across the healthcare ecosystem.
• That data is messy, multi-modal and enormously valuable.
• Modern foundation models finally make it possible to turn it into structured, trustworthy insight at the point of care and across populations.
• Your job is to make that happen, safely and at scale.

• This is a hands-on role.
• You'll write production code, ship prototypes to real users, set technical direction, and mentor the engineers who build alongside you.
• This work will require interactions with solution engineers, product managers, sales, and marketing.

What You Bring

• 7+ years building and shipping AI/ML systems, including 2+ years putting LLM-powered products into production for real users.
• Hands-on depth in modern LLM engineering: RAG, agents and tool use, structured outputs, prompt and context engineering, and the trade-offs between frontier APIs and open-weight models.
• A track record of building ML infrastructure others depend on - serving, pipelines, model and prompt versioning, CI/CD, monitoring.
• A rigorous approach to evaluation: you've designed eval sets and metrics, and you don't ship on vibes.
• Strong Python and software engineering fundamentals; fluency in PyTorch and the Hugging Face ecosystem.
• Production experience on a major cloud (AWS preferred) with containers, and infrastructure as code.
• Sound judgment about safety, privacy and reliability when models touch sensitive data.
• Clear writing and communication; you can explain model behavior and risk to clinicians, product leaders and executives.
• BS in Computer Science, Statistics or a related field, or equivalent experience.
• Are in the Boston metro and excited to collaborate in person on a hybrid schedule, or are remote (EST/CST) but willing to travel for in person collaboration occasionally.

Bonus Points

• Healthcare or clinical NLP experience, especially with FHIR, C-CDA, clinical terminologies or HIPAA-regulated data.
• Fine-tuning, distillation or preference optimization of LLMs at meaningful scale.
• Built MCP servers or multi-agent systems used in production.
• Inference optimization: quantization, speculative decoding, batching, GPU cost management.
• Designed and executed pre-training of transformer models.
• Open-source contributions, publications or talks in ML, NLP or LLM systems.
• Experience as the first or founding ML engineer at a growth-stage company.
• MS or PhD in a quantitative field.

We Will Offer You

• Competitive compensation that reflects the value you bring to the team a combination of cash and equity
• Robust benefits that include health insurance, wellness benefits, 401k with a match, unlimited PTO
• Opportunity to work alongside a passionate team that is determined to help change the world (and have fun doing it)

Additional information

Please Note: Research shows that candidates from underrepresented backgrounds often don’t apply unless they meet 100% of the job criteria. While we have worked to consolidate the minimum qualifications for each role, we aren’t looking for someone who checks each box on a page; we’re looking for active learners and people who care about disrupting the current healthcare system with their unique experiences.

We do not conduct interviews by text nor will we send you a job offer unless you've interviewed with multiple people, including the Director of People & Talent, over video interviews. Job scams do exist so please be careful with your personal information.