BillionToOne

Ready to redefine what's possible in molecular diagnostics? Join a team of brilliant, passionate innovators determined to transform healthcare. At BillionToOne, we've built a category-defining, publicly traded company on Nasdaq where transparency fuels trust, collaboration drives breakthroughs, and every contribution moves the needle on our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we build products that are 10x better than anything that exists today. Our scientists, engineers, sales executives, and visionaries are united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion, and every innovation you contribute helps remove the fear of the unknown from some of life's most critical medical moments. If you're driven by purpose, energized by innovation, and ready to help shape the future of precision medicine at scale, this is where you belong. As BillionToOne scales rapidly, we are building a world-class Commercial Data & Applied AI team. We are currently seeking a highly motivated Senior AI Engineer I to support the design and implementation of AI and automation solutions that optimize operations across our commercial, billing, and customer experience teams. This is a full-time senior role for engineers excited about applying LLMs, AI, and automation to real-world business challenges in healthcare. You will have the opportunity to join a new team and help shape the vision and culture. You will collaborate cross-functionally with stakeholders in Sales, Marketing, Revenue Operations, Billing, Customer Experience, and IT to identify high-impact opportunities for AI-driven solutions that improve scalability and efficiency. We are builders at heart. We value a strong sense of ownership, intellectual curiosity, and a bias toward action. This is a hybrid role requiring 2-3 days per week on-site in Menlo Park with the team. Responsibilities: Build and deploy LLM-powered applications (retrieval systems, AI agents, workflow automation, vector storage) that integrate with internal systems and data sources Partner with business stakeholders to identify automation opportunities, scope requirements, and define success metrics Build lightweight data pipelines and analytics to support AI applications and measure their impact Own projects end-to-end: from prototyping and iteration through production deployment and monitoring Establish best practices for prompt engineering, evaluation, and responsible AI use as the team scales Develop and lead internal training sessions on LLM fundamentals, prompt engineering, and AI-assisted development tools Qualifications: 5+ years of experience in software engineering, data science, or ML engineering Hands-on experience building applications with LLM APIs (OpenAI, Anthropic, etc.) Strong Python proficiency and comfort with SQL and relational databases Experience deploying and maintaining production systems Familiarity with AWS Excellent communication skills and ability to translate business problems into technical solutions Self-directed and comfortable with ambiguity in a 0-to-1 environment Nice-To-Haves: Previous entrepreneurial experience Experience with retrieval architectures, vector databases, and embedding models Familiarity with agent frameworks or workflow orchestration tools Experience with traditional ML frameworks (scikit-learn, PyTorch, TensorFlow) Prior work in healthcare, biotech, or other regulated industries Benefits And Perks: Working alongside brilliant, kind, passionate and dedicated colleagues, in an empowering environment, toward a global vision, striving for a future in which transformative molecular diagnostics can help millions of patients Open, transparent culture that includes weekly Town Hall meetings The ability to indirectly or directly change the lives of hundreds of thousands patients Multiple medical ben

Join a team of brilliant, passionate innovators who wake up every day determined to transform healthcare. At BillionToOne, we've built something extraordinary—a culture where transparency fuels trust, collaboration drives breakthroughs, and every voice matters in our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we strive to build products that are 10x better than anything that exists today. Our people are our greatest asset: talented scientists, engineers, sales professionals, and visionaries united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion—every innovation you contribute helps remove fear of unknown from some of life's most critical medical moments. If you're driven by purpose, energized by innovation, and ready to help build the future of precision medicine, this is where you belong. We are currently looking for a high-performing Senior Software Engineer, Prenatal to join our dynamic software engineering team. Software engineers at BillionToOne work in highly collaborative and interdisciplinary teams of clinicians, computational biologists, and other engineers to robustly scale personalized genomic medicine to millions of patients. If you have experience performing in a full life-cycle development, love seeing your work positively affect your colleagues and patients, and thrive in a fast-paced entrepreneurial environment, this could be a great opportunity for you. In this role, you can have an impact both through many small tools and large product development. This role is a hybrid (onsite 2-3 days/week) position. Projects you may work on include: Build a seamless digital experience so clinicians and patients across a diversity of care centers and socioeconomic status can have access to BillionToOne’s highly complex genetic testing Help digitize laborious and error-prone paper-based workflows at busy OBGYN clinics Enable better transfer of care through portable electronic medical records  Infuse joyful experiences into pregnancy Technologies we use include: Python, Django, Postgres, React, Typescript, AWS, Salesforce, and emerging AI-assisted coding environments (e.g., Cursor, GitHub Copilot, Claude Code) Responsibilities: Build and maintain robust applications and systems using React, Typescript, Django, Postgres, and other libraries. Collaborate with product design and product management to deliver delightful experiences for patients and providers. Foster a knowledge sharing culture within the team, contributing to the growth and development of colleagues through mentorship and collaborative learning. Demonstrate a creative and out-of-the-box mindset, offering innovative solutions and approaches to complex technical challenges. Prioritize quality by writing comprehensive unit tests and ensuring adequate test coverage across all components and modules. Demonstrate a strong sense of ownership and take responsibility for end-to-end project delivery. The ideal candidate will thrive in an environment where they have the autonomy to make informed decisions and take the initiative to drive projects forward. Champion engineering excellence through architectural best practices, code quality standards, and thoughtful code reviews that emphasize both functionality and security. Apply a security and compliance mindset ensuring adherence to relevant regulations while implementing appropriate safeguards for sensitive patient information. Confidently challenge ideas and assumptions from stakeholders when necessary, while at the same time, leverage their expertise and insights to improve the overall solution. Requirements: 5+ years of professional software development experience with a proven track record of delivering complex projects and adhering to best practices Deep experience with modern frontend technologies, specifically with Typescript, React, and CSS

Ready to redefine what's possible in molecular diagnostics? Join a team of brilliant, passionate innovators who wake up every day determined to transform healthcare. At BillionToOne, we've built something extraordinary—a culture where transparency fuels trust, collaboration drives breakthroughs, and every voice matters in our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we strive to build products that are 10x better than anything that exists today. Our people are our greatest asset: talented scientists, engineers, sales professionals, and visionaries united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion—every innovation you contribute helps remove fear of the unknown from some of life's most critical medical moments. If you're driven by purpose, energized by innovation, and ready to help build the future of precision medicine, this is where you belong. We are currently looking for a high-performing Senior Software Engineer to join our dynamic prenatal software engineering team. Software engineers at BillionToOne work in highly collaborative and interdisciplinary teams of clinicians, computational biologists, and other engineers to robustly scale personalized genomic medicine to millions of patients. If you have experience working across the full development lifecycle, love seeing your work positively affect your colleagues and patients, and thrive in a fast-paced entrepreneurial environment, this could be a great opportunity for you. In this role, you can have an impact both through many small tools and large product development. This role is a hybrid (onsite 3 days/week) position**.** Projects you may work on include: Scaling and future-proofing core systems to support rapid volume growth, enterprise workloads, and long-term platform expansion. Building shared platform libraries and modular, domain-aligned services that reduce coupling, improve maintainability, and enable teams to integrate and deliver independently. Driving core architectural initiatives including service boundaries, data flows, observability patterns, and modernization of legacy components to enhance reliability and developer velocity. Establishing foundational infrastructure and automation that strengthens deployment workflows, improves system health visibility, and enables consistent, high-quality engineering execution. Technologies we use include: Python, Django, Postgres, React, Typescript, AWS, Heroku, Salesforce, and emerging AI-assisted coding environments (e.g., Cursor, GitHub Copilot, Claude Code) Responsibilities: Design, build, and operate scalable, high availability backend services, APIs, and data integrations that power customer facing product experiences Lead technical delivery across the full lifecycle: architecture, design, implementation, testing, deployment, and ongoing operations Collaborate closely with product, design, and cross functional engineering teams to deliver performant, reliable, and intuitive platform capabilities Develop clean abstractions and platform APIs that simplify complex LIS workflows while balancing developer velocity with long term system stability Build and maintain secure, reliable cloud infrastructure on AWS, including compute environments, networking, container orchestration, storage, and environment automation Implement CI/CD pipelines, Infrastructure as Code, configuration management, and automated environment provisioning to standardize and accelerate delivery Embed observability and operational excellence into the platform by default through robust monitoring, logging, alerting, and reliability patterns Ensure the scalability, maintainability, and overall health of backend and cloud systems as the platform grows to support large enterprise workloads and future global expansion Foster a culture of ownership, technical excellence, lear

Ready to redefine what's possible in molecular diagnostics? Join a team of brilliant, passionate innovators who wake up every day determined to transform healthcare. At BillionToOne, we've built something extraordinary—a culture where transparency fuels trust, collaboration drives breakthroughs, and every voice matters in our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we strive to build products that are 10x better than anything that exists today. Our people are our greatest asset: talented scientists, engineers, sales professionals, and visionaries united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion—every innovation you contribute helps remove fear of unknown from some of life's most critical medical moments. If you're driven by purpose, energized by innovation, and ready to help build the future of precision medicine, this is where you belong. We are currently looking for a high-performing Senior Software Engineer to join our dynamic software engineering Oncology team. Software engineers at BillionToOne work in highly collaborative and interdisciplinary teams of clinicians, computational biologists, and other engineers to robustly scale personalized genomic medicine to millions of patients. If you have experience performing in a full life-cycle development, love seeing your work positively affect your colleagues and patients, and thrive in a fast-paced entrepreneurial environment, this could be a great opportunity for you. In this role, you can have an impact both through many small tools and large product development. This role is a hybrid (onsite 2-3 days/week) position. Projects you may work on include: Build a seamless digital experience so clinicians and patients across a diversity of care centers and socioeconomic status can have access to BillionToOne’s highly complex genetic testing Help digitize laborious and error-prone paper-based workflows at busy Oncology clinics Enable better transfer of care through portable electronic medical records Technologies We Use: Python, Django, Flask, Postgres, AWS, Alpine.js, HTMX, Salesforce, and emerging AI-assisted coding environments (e.g., Cursor, GitHub Copilot, OpenAI). Responsibilities: Collaborate with talented engineers to design and develop our services, data processing pipelines, and interfaces, driving innovation and efficiency Build user-facing features to optimize performance and reliability, enhancing overall user experience Elevate BTO Oncology’s backend systems, including the test order record database, third-party integrations, test scheduling and reports management software, and distributed systems architecture, to ensure they meet the highest standards Demonstrate a creative and out-of-the-box mindset, offering innovative solutions and approaches to complex technical challenges Prioritize quality by writing comprehensive unit / integration / end-to-end tests and ensuring superior test coverage across all components and modules. Highly skilled in writing technical documentation and validation reports that assure correct functionality of medical informatics systems Demonstrate a strong sense of ownership and take responsibility for end-to-end project delivery. The ideal candidate will thrive in an environment where they have the autonomy to make informed decisions and take the initiative to drive projects forward Collaborate cross-functionally, actively seeking input from team members and fostering a positive and inclusive work environment Qualifications: 5+ years of professional software development experience with a proven track record of delivering complex projects and adhering to best practices Expertise in Python backend frameworks (e.g., Django or Flask), delivering high-quality, scalable code Strong foundation in cloud services, preferably AWS, including ECS, S3, AWS Batch, EC2,

BillionToOne is a next-generation molecular diagnostics company dedicated to developing powerful and accurate diagnostic tests that are accessible to all. Our innovative QCT molecular counting technology significantly enhances the resolution of disease detection using cell-free DNA by over a thousandfold. This groundbreaking technology is integral to our product offerings, including one of our flagship products, Unity Complete™, the only non-invasive prenatal screen capable of assessing fetal risk for both common recessive conditions and aneuploidies from a single maternal blood sample. Leveraging the same molecular counting technology, we've expanded our impact into oncology in 2023 with a pioneering liquid biopsy test, Northstar, that combines treatment selection with monitoring. To date, over 500,000 patients have benefited from our innovative and precise diagnostic tests, and our Annual Recurring Revenue (ARR) has grown from $0 to $125 million in the last ~4 years. BillionToOne has successfully raised close to $400 million in funding, with a notable $130 million Series D round completed in June 2024, resulting in a company valuation of over $1 billion. This funding has come from prestigious global institutional investors, including Hummingbird, Adams Street Partners, Neuberger Berman, Baillie Gifford, and Premji Invest. BillionToOne has recently been recognized by Forbes as one of America's Best Startup Employers for 2024, highlighting the company's exceptional work environment and commitment to innovation. Our team has grown significantly and we now proudly employ over 400 highly skilled individuals. Despite substantial growth, we have successfully maintained the unique culture that has defined BillionToOne from inception, continuing to cultivate a team that is not only diverse and passionate but also innovative. Headquartered in Menlo Park, California, with an additional facility in Union City, California, BillionToOne remains at the forefront of significant advances in molecular diagnostics, evidenced by the recent announcement of clinical outcomes data for its Unity Fetal Risk Screen and new advancements in cancer diagnostics. For more detailed information about BillionToOne and its groundbreaking work, please visit our website at www.billiontoone.com. We are currently looking for a high-performing Senior Software Engineer, Frontend to join our dynamic software engineering team. Software engineers at BillionToOne work in highly collaborative and interdisciplinary teams of clinicians, computational biologists, and other engineers to robustly scale personalized genomic medicine to millions of patients. If you have experience performing in a full life-cycle development, love seeing your work positively affect your colleagues and patients, and thrive in a fast-paced entrepreneurial environment, this could be a great opportunity for you. In this role, you can have an impact both through many small tools and large product development. This role is a hybrid (onsite 2-3 days/week) position. Projects you may work on include: Build a seamless digital experience so clinicians and patients across a diversity of care centers and socioeconomic status can have access to BillionToOne’s highly complex genetic testing Help digitize laborious and error-prone paper-based workflows at busy Oncology and Prenatal clinics Enable better transfer of care through portable electronic medical records Technologies We Use: Python, Django, Postgres, AWS, React, Typescript, Alpine.js, HTMX, Salesforce, and emerging AI-assisted coding environments (e.g., Cursor, GitHub Copilot, OpenAI). Responsibilities: Collaborate with talented engineers to design and develop our backend services, data processing pipelines, and interfaces, driving innovation and efficiency Build user-facing frontend features to optimize performance and reliability, enhancing overall user experience. Demonstrate a creative and out-of-the-box mindset, offering innovative solutions a