Senior Software Engineer, Prenatal

Menlo Park, CA

A Rare Opportunity to Shape the Future of Genomics

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. 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:

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 workloadsand future global expansion
Foster a culture of ownership technical excellence learning,and continuous improvement within the engineering team
Apply AI-assisted toolingand workflows to improve developer productivity automate routine engineering tasks enhance code quality,and accelerate troubleshooting

Qualifications:

5 - 7 years of professional software development experience with a proven track record of delivering complex projects adhering to best practices
Deep understandingand experience using web frameworks like Djangoand FastAPI
Strong system designand architecture capabilities applying domain-driven designto translate complex business domains into clear scalable serviceand data boundaries.
Familiarity with modern AI-driven development practicesand tools.
Strong foundation in cloud services preferably AWS including ECS S3 AWS Batch EC2,and AWS Lambda enabling effective architectureand management of complex systems
Excellent communicationand collaboration skills with the abilityto work effectively in a team-oriented environment
Excited about working in-person with our team in Menlo Park

Benefits And Perks:

Working alongside brilliant kind passionateand 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 abilityto indirectly or directly change the livesof 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 eligible employees (16 weeks paid at 100%)
Supplemental fertility benefits coverage
Retirement savings program including a 4% Company match
Increase paid time off with increased tenure
Latestand greatest hardware (laptop lab equipment facilities)
Daily on-site lunches provided from top eateries
A varietyof perks on campus (stateoftheart gym restaurant)
Free on-site EV charging (compatible with all EVs including Tesla)

At BillionToOne we are proudto offer a combinationof a (1) base pay range (actual amount offered is based on experienceandsalary/equity options split that the candidate chooses) (2) generous equity options offering (3) corporate bonus program on topof (4) industry leading company benefits (free healthcare options 401k match very generous fully paid parental leave etc.). For this position we offera total compensation packageof $300806 per year includinga base pay rangeof $192932 - $214369 per year. BillionToOne is an equal opportunity employer. We do not discriminate onthe basisof race religion color national origin gender sexual orientation age marital status veteran status or disability status. For more information about how we protect your information we encourage you to review our Privacy Policy. BillionToOne is a next-generation molecular diagnostics company ona missionto make powerful accurate diagnostic tests accessible toeveryone. Our revolutionary QCT molecular counting technology enhances disease detection resolution by overa thousandfold using cell-free DNA,a breakthrough that has already transformedthe livesof over half amillion patients worldwide.

Our Impact

Unity Complete™ is the only non-invasive prenatal screen capableof assessing fetal riskfor both common recessive conditionsandanueploidies froma single maternal blood sample. Unity Confirm™ enables non-invasive confirmation for high-risk screening results throughthe captureof intact circulating fetal cells using BillionToOne’s Fetal Cell Capture™ Technology. Our Northstar® liquid biopsy test uniquely combines treatment selectionwith real-time monitoring giving oncologists unprecedented precisionin cancer care.

Our Growth

From $0to $400M+ annualized revenue run-ratein just 6 years. In 2025 we completed oneofthe most successful IPOs fora medical diagnostics company buildingon nearly $400M in private funding including our $130M Series D in 2024and backedby world-class investors including Hummingbird Adams Street Partners Neuberger Berman Baillie Gifford,and Premji Invest.

Our Recognition

Forbes named us oneof America's Best Startup Employers for 2025and we're Great Place to Work certified with 100%oftheir people willingto go the extra mile even as we've scaledto over700 employees.

Our Future

Headquarteredin Menlo Parkwith facilitiesin Union City CA,and anew lab openingin Austin TX in 2027 we're continuingto pushthe boundariesof what's possiblein molecular diagnostics. We're just getting started. Readyto help us change the world one moleculeat atime? Learn more atbilliontoone.com