Software Engineering Intern

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 2025, highlighting the company's exceptional work environment and commitment to innovation.

Our team has grown significantly and 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.

We are seeking a passionate and motivated Software Engineering Intern to join our dynamic engineering team for a summer internship program. As an intern, you'll work alongside experienced engineers, clinicians, and computational biologists across multiple product lines, contributing to meaningful projects that help scale personalized genomic medicine to millions of patients. This is an excellent opportunity to gain hands-on experience in healthcare technology while making a real impact on patient care. This is a full-time hybrid position (onsite 2-3 days/week).

Example Projects:

• Portal Enhancements: Develop new features for our provider and patient portals, such as implementing automated notification systems or creating intuitive data visualization dashboards for test results

• AI-backed Services: Create new software services that are AI driven such as insurance card scanning or lab monitoring

These projects will give you hands-on experience while contributing to meaningful improvements in healthcare delivery.

Responsibilities:

• Write clean, well-documented code following team standards and best practices

• Participate in code reviews and contribute to technical discussions

• Create and maintain comprehensive test suites for your code

• Document your work and contribute to technical documentation

• Present your projects and findings to the team

Requirements

• Currently enrolled in a Bachelor's or Master's degree program in Computer Science or related field

• Demonstrated programming experience with Python through coursework or projects

• Basic understanding of databases (SQL) and web development concepts

• Strong problem-solving skills and eagerness to learn

• Clear written and verbal communication skills

• Available for full-time summer internship (10-12 weeks)

• Excited about working in-person with our team in Menlo Park (2-3 days/week)

• Passionately curious about the fields of healthcare and biotechnology

Nice-to-haves

• Previous project experience (personal, academic, or hackathon projects)

• Familiarity with any web framework (Django, Flask, etc.)

• Basic understanding of version control (Git)

• Experience working with LLMs (GPT, Claude, etc.)

• Experience working with REST APIs

• Basic understanding of cloud services concepts

• Experience with prompt engineering or LLM application development

Benefits And Perks

• Working with a team of ‘rockstars’ who bring out the best in everyone

• Open, transparent culture that includes weekly Town Hall meetings

• The ability to indirectly or directly change the lives of hundreds of thousands patients

• Free daily on-site lunches provided from top eateries

• Latest and greatest hardware (laptop, lab equipment, facilities)

• 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 (1) competitive base pay, and (2) the opportunity for professional growth.

For this position, the base pay rate is $4,333 per month.

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.