Senior Full Stack Engineer (Back-End)

Job description

⚠️ Please read first This is a full-time, in-person role based in San Francisco (Presidio) - we work from the office 5 days a week . You must be based in the Bay Area or willing to relocate before starting . We require US work authorisation , but are open to O-1 visa sponsorship for truly exceptional candidates. Senior Full Stack Engineer (Back-End) What You'll Do: You’ll write and ship full-stack features end to end, from the agent runtime and backend APIs, to the web and desktop UI that users interact with every day. We're still ~15 people and shipping to our first paying users. You won't just be building features, you'll be making the decisions that determine whether this system holds at 1000x the current load. You'll work directly with our CTO. Here are a few examples of the kinds of things you might work on: Build and operate the sandbox infrastructure where agents execute code, process isolation, resource limits, secure credential handling across thousands of concurrent sessions. Design the deployment and migration pipeline for a Cloudflare Workers + Fly.io architecture, including blue-green rollouts and canary patterns. Instrument real-time workloads end to end: SSE streamin...