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 seeking a Senior Scientist to further develop our product pipeline. We are looking for a quantitative biologist, biophysicist, or bioengineer, both able to design complex high-throughput molecular biology experiments & analyze complex, quantitative data that the experiments generate. Our Senior Scientists serve as principal investigators with significant resources and direct reports. This is an impactful position, appropriate for an inspired scientist and extraordinary problem solver. The Senior Scientist position is an onsite position located at our state of the art Menlo Park laboratory. 

Responsibilities:

• Learn, use and modify our custom R/Python code for experimental design purposes, and complement them with bioinformatic tools as needed
• Plan and develop the research strategy
• Design (and be able to perform) experiments to validate diagnostic/screening assays
• Analyze experiments and troubleshoot them as necessary
• Read the literature from chemistry and molecular biology to synthetic biology, bioengineering, and statistical learning fields to find creative opportunities for further improvements in our assays
• Mathematically/computationally model experimental processes to iterate on the research strategy and assay development

Requirements:

• PhD in biological sciences, bioengineering, biophysics, or related discipline with molecular biology lab experience
• A deep quantitative understanding of and approach to biology
• A strong background in physics, applied mathematics, or mathematical biology (i.e., you intuitively understand concepts such as error propagation, probability distributions, Markov models, Monte Carlo simulations, phase diagrams etc.)
• Ability to analyze data and model biological processes in R or Python
• Knowledge of data structures and algorithms and familiarity with industry tools (Github, command line, AWS)

Nice-to-Haves:

• Next-generation-sequencing experience
• A deep understanding of or experience with nucleic acid chemistry

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 benefit options; employee premiums paid 100% of select plans, dependents covered up to 80%
• Extremely generous Family Bonding Leave for new parents (16 weeks, paid at 100%)
• Free UNITY Complete NIPT testing for employees & spouses
• Supplemental fertility benefits coverage 
• Retirement savings program including a 4% Company match
• Increase paid time off with increased tenure
• Latest and greatest hardware (laptop, lab equipment, facilities)
• Free daily on-site lunches provided from top eateries
• A variety of perks on campus (state of the art gym, restaurant)
• Free on-site EV charging (compatible with all EVs, including Tesla)

At BillionToOne, we are proud to offer a combination of a (1) base pay range (actual amount offered is based on experience and salary/equity options split that the candidate chooses), (2) generous equity options offering, (3) corporate bonus program, on top of (4) industry leading company benefits (free healthcare options, 401k match, very generous fully paid parental leave, etc.).

For this position, we offer a total compensation package of $246,666 per year, including a base pay range of $135,252 - $156,060 per year.

BillionToOne is an equal opportunity employer. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.

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About BillionToOne

BillionToOne is a next-generation molecular diagnostics company on a mission to make powerful, accurate diagnostic tests accessible to everyone. Our revolutionary QCT molecular counting technology enhances disease detection resolution by over a thousandfold using cell-free DNA—a breakthrough that's already transformed the lives of over half a million patients worldwide.

Our Impact: We've pioneered game-changing diagnostic solutions that are redefining industry standards. Unity Complete™ stands as the only non-invasive prenatal screen capable of assessing fetal risk for both common recessive conditions and aneuploidies from a single maternal blood sample. In oncology, our Northstar® liquid biopsy test uniquely combines treatment selection with real-time monitoring, giving oncologists unprecedented precision in cancer care.

Our Growth: From $0 to $125 million in Annual Recurring Revenue in just four years. We've raised close to $400 million in funding, including a $130 million Series D round in June 2024, achieving a valuation of over $1 billion. This backing comes from world-class investors including Hummingbird, Adams Street Partners, Neuberger Berman, Baillie Gifford, and Premji Invest.

Our Recognition: Forbes recently named us one of America's Best Startup Employers for 2025, and we were awarded Great Place to Work certification in 2024—with an incredible 100% of our people reporting they are willing to give extra to get the job done. These honors recognize not just our innovation but the exceptional culture we've cultivated—one that remains authentically collaborative and transparent even as we've scaled.

Our Future: Headquartered in Menlo Park with facilities in Union City, California, we're continuing to push the boundaries of what's possible in molecular diagnostics. Recent clinical outcomes data for Unity Fetal Risk Screen and new advances in cancer diagnostics prove we're just getting started.

At BillionToOne, you'll join a diverse team of passionate innovators who believe that the best science happens when brilliant minds collaborate openly, think boldly, and never lose sight of the patients whose lives depend on our work.

Ready to help us change the world, one diagnosis at a time?

Learn more at www.billiontoone.com