Senior Full-Stack Engineer — Real-Time Systems (SF)

Sauna by Wordware; San Francisco (CA); On-site; USD 180,000 - 240,000; Full time

Benefits offered by this job

Health

Dental

401(k)

PTO

Gym budget

Lunch

Job summary

Sauna by Wordware, based in San Francisco, is hiring for a full-time, in-person backend/Full-Stack role. You will build end-to-end features across agent runtime, backend APIs, and web/desktop UI, operating a sandboxed environment and handling thousands of concurrent sessions.

You will join a small team near the Presidio, with strong emphasis on reliability and scale. You will work directly with the CTO, shipping new backend capabilities, tool integrations, and real-time workloads while shaping

Qualifications

• 5+ years of engineering experience building and operating backend systems in production.
• Fluency in TypeScript and comfort across the stack, with backend focus.
• Experience with real-time systems (WebSockets/SSE) in production.
• Distributed systems intuition and opinions on consistency tradeoffs.
• Shipped infrastructure used by real users, not just internal tooling.

Responsibilities

• Write and ship full-stack features end to end, from the agent runtime and backend APIs to the web/UI users interact with daily.
• Build and operate sandbox infrastructure for agents, with secure credential handling and scaling.
• Design deployment pipelines and migrations (Cloudflare Workers + Fly.io) with blue-green rollouts and canaries.
• Instrument real-time workloads end to end: streaming, queues, and model routing.
• Reduce operational toil with structured logging, tracing, monitoring, and incident response tooling.

Skills

Backend experience

TypeScript

Real-time systems

Distributed systems

Production infrastructure

On-call experience

Tools

Cloudflare Workers

Durable Objects

Postgres

Docker

Vercel

Job description

Sauna by Wordware, based in San Francisco, is hiring for a full-time, in-person backend/Full-Stack role. You will build end-to-end features across agent runtime, backend APIs, and web/desktop UI, operating a sandboxed environment and handling thousands of concurrent sessions.

You will join a small team near the Presidio, with strong emphasis on reliability and scale. You will work directly with the CTO, shipping new backend capabilities, tool integrations, and real-time workloads while shaping