Senior Full-Stack Engineer – Onsite SF, Real-Time Backend

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

Benefits offered by this job

Health insurance

Dental insurance

401(k)

Generous PTO

Gym budget

Lunch

Job summary

Sauna by Wordware in San Francisco (Presidio) is seeking a senior backend engineer to own the sandbox, backend APIs, and web UI accessibly by users. You will help scale and harden the system to handle thousands of concurrent sessions and evolving workloads.

You will design deployment pipelines for Cloudflare Workers and Fly.io, instrument real-time workloads, and ship new backend capabilities while reducing toil for a small, dedicated team.

Qualifications

• 5+ years of engineering experience building and operating backend systems in production.
• Fluent in TypeScript; comfortable across the stack with backend focus.
• Experience with real-time systems (WebSockets, SSE, event streaming, or queues).

Responsibilities

• Build and operate sandbox infrastructure where agents run code with isolation and secure credentials.
• Design deployment/migration pipelines for Cloudflare Workers + Fly.io with blue-green and canary patterns.
• Instrument end-to-end real-time workloads: SSE streaming, queues, model routing.
• Ship backend capabilities, tool integrations, and scheduled tasks used by real users.
• Reduce toil with structured logging, tracing, monitoring, and incident response tooling.

Skills

Backend engineering

TypeScript

On-call experience

Real-time systems

Distributed systems

Tools

Cloudflare Workers

Durable Objects

Postgres

Docker

Vercel

SST

Job description

Sauna by Wordware in San Francisco (Presidio) is seeking a senior backend engineer to own the sandbox, backend APIs, and web UI accessibly by users. You will help scale and harden the system to handle thousands of concurrent sessions and evolving workloads.

You will design deployment pipelines for Cloudflare Workers and Fly.io, instrument real-time workloads, and ship new backend capabilities while reducing toil for a small, dedicated team.