Senior Software Engineer

About the company

Our client is a seed-stage, venture-backed AI startup in San Francisco building voice and billing automation for an overlooked corner of US healthcare: emergency medical services. Most ambulance agencies collect only about 30% of what they bill, against 85 to 95% across the rest of healthcare, and the product uses AI to close that gap. It is already live with well over a hundred ambulance agencies and billing offices, has recently signed its first enterprise contract with one of the largest ambulance agencies in the country, and has just launched a second product. The team is three people today, which is why these are engineers number four and five.

The role

You would join the founding team as engineer number four or five, reporting straight to the CEO on a flat team with no managers. Roughly 40% of the time goes to building new features end to end — voice agents that call insurance payers, LLM pipelines that contest claim denials. About 30% goes to the backend and the infrastructure, so the systems hold up as enterprise volume arrives. The rest is product thinking: deciding what to build, how it should look and feel, and why. You would spend real time with EMTs, billers, fire chiefs and operations leaders, so explaining your work clearly out loud matters here as much as writing it.

What you'll do

• Build new features end to end, including voice agents that call insurance payers and LLM pipelines that contest claim denials
• Improve the backend and the infrastructure, and refactor, so the systems hold up as enterprise volume grows
• Shape the product with your own taste — what to build, how it should look and feel, and why
• Work directly with EMTs, billers, fire chiefs and operations leaders to understand what they actually need
• Give and take feedback on a flat team where everyone picks up work from each other

Nice to have

• Background in healthcare, emergency medical services, insurance billing or clinical work
• Holds or has held an EMT or NREMT certification
• Production experience with TypeScript and React on AWS or GCP, named in a dated role
• Has built LLM pipelines or voice AI agents in production
• Has worked directly with customers or non-technical users to decide what to build
• A computer-science bachelor's degree from a top-30 US program, or time at a company known for strong engineering
• Senior or staff individual contributor with well over five years of building experience

Tech stack

TypeScript and React across the stack, running on AWS and GCP, with LLM pipelines and voice AI agents at the centre of the product. The team works AI-assisted and agentically day to day, though the client is wary of engineers who can only prompt and cannot build a system as a whole. Go is in the codebase but familiarity with it is not important. Older stacks with no modern TypeScript and cloud work are a concern.

Compensation & logistics

• $170k–$230k base plus competitive equity — the top of the range is for strong senior and staff engineers
• Hybrid in San Francisco — four days a week in the South Park office
• Open to candidates who need no sponsorship and to simple visa transfers such as an H-1B transfer or OPT; the client will not file a new, first-time visa sponsorship
• Health, vision and dental fully covered, unlimited PTO, and lunch and dinner provided on office days
• Two hires on this role — engineers number four and five, on a flat team with no managers
• Interview process: a 30-minute culture and communication call with the CEO, a 30-minute live coding session with two engineers, a 30-minute product assessment, then a two to three hour on-site in San Francisco covering system design and a team lunch
• Full-time