Senior AI Engineer

Why Weave Exists At Weave, our mission is to evolve how therapeutic knowledge is captured, transformed, and communicated throughout drug development. We do this by equipping human experts with AI instruments to enable drugs to be brought to patients as rapidly, safely, and inexpensively as possible. The Weave Platform streamlines regulatory workflows from start to finish by intelligently, creatively, and effectively infusing every step with AI. Together with our customers, Weave is designing and building the AI workbench for the entire therapeutic lifecycle. The Role & Your Mission We’re seeking a hands-on Senior AI Engineer who can bridge the gap between data and biomedical expertise while delivering robust backend code. Reporting to the Head of Applied AI, your primary focus will be building the LLM-facing components of our backend service, while ensuring the AI models consistently produce accurate, grounded, useful, and reliable outputs under real-world load. The ideal candidate thrives in the full development cycle: taking concepts from initial conception through rigorous experimentation and testing, all the way to production deployment. You won't get lost in low-ROI side quests, but instead will maintain velocity with unwavering focus on the core value of your tasks. We value pragmatic problem-solving over flashy technology and buzz words, robustly tested solutions over demoware. We're building solutions that actually work—simple, thoroughly tested, and rock-solid reliable. If you believe the best technology is the one that consistently delivers results, you'll fit right in. What You'll Own Writing production-ready backend code for LLM-facing components of our backend service Building automated evaluation systems for LLM-dependent code, including regression datasets, quality metrics, failure taxonomies, and release gates Designing and validating LLM-based solutions (prompts, context-construction pipelines, tool-calling workflows, structured outputs, and retrieval systems) and proving their effectiveness with real data and meaningful metrics Measuring and improving LLM solutions quality, grounding, consistency, latency, token usage, and cost What You’ll Bring Direct experience building, shipping and operating meaningful LLM-powered products or workflows in production Scientific or quantitative background in machine learning, statistics, computer science, biology, chemistry, or a related field; experience in biotech, pharmaceuticals, or another life-sciences setting is preferred Humble, hungry, and smart attitude Ability to move quickly while maintaining a high bar for correctness and reliability Clear technical judgment: able to explain trade-offs, prioritize high-value work, and stop low-ROI experimentation Bonus: History of working at early-stage, product-based startups (<100 people) Experience developing software in regulated or high-accountability environments What We Offer The opportunity to work at a modern, cutting-edge healthcare technology company devoted to meaningful positive impact on human life. Collaboration, velocity, and customer obsession are our baseline, demonstrations of craftsmanship and ROI are celebrated. Competitive salary ($175,000 - $215,000) and equity packages. Comprehensive health, dental and vision insurance ️ Take care of you and yours: generous PTO, parental leave, OneMedical, TalkSpace, Teladoc. Career development opportunities within a company entering a growth phase. Hybrid in San Francisco with in-office days Tues/Wed/Thurs and flexibility to work remote Mon/Fri. Equal Opportunity Employer: We are committed to creating a diverse environment and are proud to be an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. This organization participates in e-Verify: Notice of E-Verify Participation Notice of Right to Work