Sully.ai

Senior Software Engineer, Research (Contract to Hire)

San Francisco, US Full-time

About Us
At Sully.ai, We’re Building the Most Impactful Healthcare Company on Earth

We believe that access to a great doctor is a basic human right. Today, that’s not a reality. Delays, misdiagnoses, administrative chaos, and burnout plague the system.

Our Mission: One Human, One Doctor. We build AI teammates that augment clinicians — scribes, nurses, receptionists, translators — all powered by our own world-class models and deployed in real-world care.

Our Traction

  • 450+ organizations signed 16 months

  • AI agents cut admin by ~2.8 hours daily and reduce onboarding 85%.

  • 5M+ Clinical Tasks completed to date, serving 36+ specialties.

  • Raised $25M from YC, Eric Yuan, Amity, Semper Virens

  • Patented AI architecture (MedCon-1) outperforms GPT-4.5, Gemini, Claude on clinical reasoning tasks

_ Sully requires A-players capable of 4 months = 1 year output. _

This role is structured as a Contract-to-Hire position with a 60-day trial period. Sully.ai maintains an exceptionally high performance bar, and this structure ensures mutual alignment before transitioning to full-time

What You’ll Do

  • Build and optimize core research infrastructure: evaluation pipelines, agent workflows, hallucination detectors, coding benchmarks, and research→production integrations.

  • Design, implement, and scale agentic systems across backend, frontend, and model integrations, collaborating closely with research and co-founders.

  • Own reliability, observability, and performance across agents (logging, tracing, instrumentation, safety checks).

  • Ship research-proven features into production within 7 days, end-to-end.

  • Develop shared tools, SDKs, and internal products that accelerate iteration across Research, QA, and Engineering.

What You _ Must _ Bring

  • Senior-level full-stack engineering experience in React, TypeScript, and Node.js.

  • Proven ability to design, ship, and scale LLM-powered applications.

  • Expertise in API design, streaming, and CI/CD pipelines.

  • Strong cloud infrastructure background ( AWS, GCP, or Azure ).

  • Track record of building reliable systems with measurable performance and error budgets.

First-Month Focus

  • Audit all cross-agent flows for UI/UX consistency, correctness, and performance gaps.

  • Implement shared components, typed schemas, and contract-driven interfaces for reliability.

  • Establish instrumentation for frontend performance, agent consistency, latency, and model round-trip tracing.

  • Improve or replace brittle evaluation or agent pipelines identified during onboarding.

  • Partner with Research to productionize at least one new capability.

90 Day OKRs

  • Deliver production-grade agentic workflows with <5% error rates across evaluation benchmarks.

  • Launch a cross-agent design system + SDK adopted by at least 2 internal teams.

  • Establish a weekly deploy + measure cadence with performance dashboards, latency budgets, and error budgets.

  • Reduce agent latency and failure rates across at least two high-volume workflows.

  • Ship multiple research-to-production integrations with measurable CSAT or accuracy gains.

Who Thrives Here

  • Entrepreneurial to your core : You think in outcomes, thrive in chaos, and take ownership without limits

  • Mission-obsessed : You’re here to save lives, not just ship features — patients and doctors are your why.

  • Impact-driven & fast-moving : You sprint toward hard problems and ship with sharp judgment.

  • Elite teammate : You raise the bar through high standards, direct feedback, and craft excellence.

Why Join Sully.ai ?
🔥 Revolutionizing the antiquated $800B+ Healthcare market

🧠 50%+ of us are ex-founders. We hire A-players, not passengers

⚡️ Speed matters - we operate with urgency, autonomy, and ownership

🧪 You’ll work on real, first-of-their-kind problems at the edge of AI and medicine

❤️ Your work helps doctors reclaim their time - and patients get better, faster care

Sully.ai is an equal opportunity employer. In addition to EEO being the law, it is a policy that is fully consistent with our principles. All qualified applicants will receive consideration for employment without regard to status as a protected veteran or a qualified individual with a disability, or other protected status such as race, religion, color, national origin, sex, sexual orientation, gender identity, genetic information, pregnancy or age. Sully.ai prohibits any form of workplace harassment. 

🚀 Y Combinator Company Info

Y Combinator Batch: S21
Team Size: 49 employees
Industry: B2B Software and Services -> Productivity
Company Description: AutonomousOS for healthcare organizations

📋 Job Details

Job Type: Full-time
Engineering Type: Full stack