Senior Software Engineers

BillionToOne (NASDAQ: BLLN) | Senior Software Engineers | Menlo Park, CA | HYBRID (2-3 days/week) | $280K-307K total comp + equity BillionToOne builds molecular diagnostics that detect disease at the single-molecule level. Our prenatal test is the only non-invasive screen for both recessive conditions and aneuploidies from one blood draw. Our oncology platform finds 50%+ more cancer treatment options than standard testing. Over 1 million tests processed to date. Every line of code here has a patient on the other end of it. Revenue grew from $0 to ~$300M in four years, guiding $415-430M for 2026. Publicly traded and GAAP profitable. You'll work alongside clinicians and computational biologists on genuinely hard problems: scaling genomic pipelines, building digital infrastructure for complex test results, and shipping systems where correctness isn't optional. Hiring across software engineering: - Senior Software Engineer, Digital Experiences (Oncology and Prenatal) - Senior Software Engineer, Oncology - Senior Software Engineer, Prenatal - Senior AI Engineer Stack: Python, Django, Postgres, React, TypeScript, AWS, Docker, Terraform, Kafka, CircleCI, Datadog. AI-assisted dev tools (Cursor, Copilot, Claude Code). Benefits: Access to the latest AI tools and models with unlimited usage to help you do your best work, 100% paid medical on select plans, 16 weeks fully paid parental leave, 401(k) with 4% match, daily catered lunch, on-site gym. Forbes Best Startup Employers 2024 & 2025. Apply: https://www.billiontoone.com/careers/open-positions