Senior Platform Engineer
Posted Updated
Description
Location: San Francisco, CA (On-site, 5 days/week)
Employment: Full-time
Seniority: Mid-Senior Level
Salary: $180,000 – $240,000
Visa: US work authorization required.
About the company
Y Combinator-backed, early-stage AI startup (~15 people) building a hybrid AI and software platform centered on a shared context engine.
The role
You’ll build and own the core execution engine (agent runtime) that manages session state, tool calls, and long-running processes — the backbone that lets AI agents operate reliably over extended sessions.
Core stack: TypeScript, Cloudflare Workers, Durable Objects, Postgres, Docker, Distributed Systems
Required
- Production experience building and operating stateful backend systems — work that outlasts the initial request
- Professional experience writing production backend code in TypeScript
- Based in the San Francisco Bay Area, or willing to relocate
Nice to have
- Experience building an agent runtime or agent harness
- Production experience with Cloudflare Workers, Durable Objects, or other actor-based runtimes
- Experience deploying long-running processes that persist across code releases
- Background at next-gen AI/agentic companies or design-first product orgs
Interview process
- Application review (resume + short questions)
- 15-min intro call
- 45-min technical interview
- System design interview
- Paid work trial (~5 days)
.
