Senior Software Engineer, Oncology

BillionToOne (YC S17) is a molecular diagnostics company with 300+ employees, unicorn status, over $400M in funding and $125M ARR. Their QCT technology enhances disease detection resolution by over a thousandfold using cell-free DNA.

As Senior Software Engineer, Oncology, you will:

• Design and develop services, data pipelines, and user interfaces
• Build backend systems including test ordering databases and third-party integrations
• Write comprehensive unit, integration, and end-to-end tests
• Author technical documentation for medical informatics systems
• Drive end-to-end project delivery with ownership mentality

Required Qualifications:

• 5+ years software development experience
• Expertise in Python backend frameworks (Django/Flask)
• Strong AWS foundation (ECS, S3, Batch, EC2, Lambda)
• Familiarity with modern AI-driven development practices
• Proven product delivery track record

Nice-to-Have:

• Healthcare software experience
• Startup/high-growth company background
• FHIR and HL7 familiarity
• Experience leveraging AI-assisted coding and debugging tools
• AI agent building or LLM deployment experience

Tech Stack: Python, Django, Flask, PostgreSQL, AWS, Alpine.js, HTMX, Salesforce, and emerging AI-assisted coding environments (e.g., Cursor, GitHub Copilot, OpenAI)

Salary: $190,081 - $211,201 base; $307,321 total compensation Hybrid: 2-3 days/week onsite in Menlo Park, CA

Benefits:

• 100% employee premium medical coverage (select plans)
• 16-week fully paid parental leave
• 4% 401(k) match
• On-site gym, dining, EV charging
• Daily catered lunches