
Senior Software Engineer
BillionToOne · Menlo Park, CA
- On site
- Full-time
- $297,321 / year
- Menlo Park, CA
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Subject: Interested in the Senior Software Engineer role at BillionToOne
Hi Jordan — I came across the Senior Software Engineer opening and wanted to reach out directly. I've spent the last few years doing exactly this kind of work, and BillionToOne stood out because…
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Job highlights
- Develop robust applications using Python, Django, React, Typescript.
- Collaborate with cross-functional teams on product development.
- Drive innovation in precision medicine and diagnostics.
- Work in a fast-paced, entrepreneurial startup environment.
- Impact lives of millions with life-changing diagnostics.
About the role
About BillionToOne
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.
Job Overview
We are currently looking for a high-performing Senior Software Engineer 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
- 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-in-JS libraries
- Have implemented frontend architecture best practices such as component systems, npm workspaces, Storybook, and Playwright testing
- Experience with web frameworks such as Django
- Familiarity with modern AI-driven development practices and tools.
- Excited about working in-person with our team in Menlo Park
Nice-to-haves
- Previous startup or entrepreneurial experience
- Experience in driving products from zero to one
- Familiarity with healthcare data and standards like FHIR and HL7
- Interest in engaging with and applying LLMs
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%)
- 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)
- 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)
Compensation
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 $297,321 per year, including a base pay range of $190,081 - $211,201 per year.
Equal Opportunity Employer
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.
For more information about how we protect your information, we encourage you to review our Privacy Policy.
About Our Impact
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 has already transformed the lives of over half a million patients worldwide.
- Unity Complete™ is the only non-invasive prenatal screen capable of assessing fetal risk for both common recessive conditions and aneuploidies from a single maternal blood sample.
- Unity Confirm™ enables non-invasive confirmation for high-risk screening results through the capture of intact circulating fetal cells using BillionToOne’s Fetal Cell Capture™ Technology.
- 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 $150M+ in Annual Recurring Revenue in just five years. In 2025, we completed one of the most successful IPOs for a medical diagnostics company, building on nearly $400M in private funding,including our $130M Series D in 2024 and backed by world-class investors including Hummingbird, Adams Street Partners, Neuberger Berman, Baillie Gifford, and Premji Invest.
Our Recognition
Forbes named us one of America's Best Startup Employers for 2025 and we're Great Place to Work certified, with 100% of our people willing to go the extra mile, even as we've scaled to over 700 employees.
Our Future
Headquartered in Menlo Park with facilities in Union City, CA, and a new lab opening in Austin, TX in 2027, we're continuing to push the boundaries of what's possible in molecular diagnostics. We're just getting started.
Ready to help us change the world, one molecule at a time? Learn more at billiontoone.com
Key skills/competency
- Senior Software Engineer
- Python
- Django
- Postgres
- React
- Typescript
- AWS
- Full-life-cycle development
- Frontend architecture
- Mentorship
Skills & topics
- Senior Software Engineer
- Software Development
- Genomics
- Diagnostics
- Python
- Django
- React
- Typescript
- AWS
- Healthcare Technology
How to get hired
- Tailor your resume: Highlight 5+ years of software development experience and specific skills in React, Typescript, and Django. Quantify achievements in project delivery.
- Showcase relevant experience: Emphasize any experience with frontend architecture best practices, AI-driven development tools, or the healthcare industry.
- Prepare for technical interviews: Be ready to discuss your experience with full life-cycle development, system design, and writing comprehensive unit tests.
- Demonstrate ownership and initiative: In your application and interviews, showcase your ability to take responsibility for end-to-end project delivery and drive projects forward.
- Express enthusiasm for the mission: Clearly articulate your passion for transforming healthcare and making diagnostics accessible to all patients.
Technical preparation
Behavioral questions
Frequently asked questions
- What is the work arrangement for the Senior Software Engineer role at BillionToOne?
- The Senior Software Engineer position at BillionToOne is a hybrid role, requiring onsite presence 2-3 days per week in Menlo Park.
- What technologies are primarily used by the software engineering team at BillionToOne?
- The primary technologies used by the software engineering team include Python, Django, Postgres, React, Typescript, and AWS. Familiarity with AI-assisted coding environments is also a plus.
- What is the salary range for the Senior Software Engineer position at BillionToOne?
- The total compensation package for this position is $297,321 per year, with a base pay range of $190,081 - $211,201 per year. This is in addition to equity options and a corporate bonus program.
- What kind of projects can a Senior Software Engineer expect to work on at BillionToOne?
- Projects involve building seamless digital experiences for clinicians and patients, digitizing paper-based workflows, enabling better electronic medical record transfers, and enhancing user experiences related to pregnancy and diagnostics.
- What are the key requirements for the Senior Software Engineer role?
- Key requirements include 5+ years of professional software development experience, deep expertise in modern frontend technologies like Typescript and React, experience with web frameworks like Django, and familiarity with AI-driven development practices.
- Does BillionToOne offer good benefits for its employees?
- Yes, BillionToOne offers industry-leading benefits including 100% employee premium coverage for select medical plans, generous paid parental leave (16 weeks), fertility benefits, a 4% 401k match, and access to state-of-the-art facilities.
- What is BillionToOne's mission and impact?
- BillionToOne's mission is to make life-changing diagnostics accessible to all. They are transforming prenatal and cancer diagnostics with technologies like Unity Complete™, Unity Confirm™, and Northstar® liquid biopsy tests, impacting millions of lives.
- What kind of growth and recognition has BillionToOne experienced?
- BillionToOne has experienced significant growth, reaching over $150M+ in ARR, completing a successful IPO, and raising substantial private funding. They have also been recognized by Forbes as a Best Startup Employer and are Great Place to Work certified.
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