Senior Software Engineer

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 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 Typ