Senior Full Stack Engineer (Back-End)

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

Benefits offered by this job

Health insurance

401(k)

Dental insurance

Equity options

Job summary

SupportFinity™ is looking for a Senior Full Stack Engineer (Back-End) in San Francisco. This full‑time role requires 5+ years of experience with engineering backend systems, focusing on building real-time applications.

The position offers a competitive salary range of $180K to $240K plus equity and a benefits package that includes health and dental insurance, as well as a 401(k).

Qualifications

• 5+ years of engineering experience building and operating backend systems in production.
• Fluent in TypeScript and comfortable working across the stack.
• Built real-time systems: WebSockets, SSE, event streaming, or message queues in production.

Responsibilities

• Write and ship full-stack features from backend APIs to UI.
• Build and operate sandbox infrastructure for executing code.
• Design deployment and migration pipeline for Cloudflare architecture.

Skills

TypeScript

Backend Systems

WebSockets

Distributed Systems

Tools

Docker

Postgres

Job description

Senior Full Stack Engineer (Back-End)

This is a full‑time, in‑person role based in San Francisco (Presidio). You must be based in the Bay Area or willing to relocate before starting. We require US work authorization, but are open to O‑1 visa sponsorship for truly exceptional candidates.

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 streaming, task queues, and multi‑model LLM provider routing.
• Ship new backend capabilities, tool integrations, scheduled task execution, memory indexing, and see them used by real people the same week.
• Reduce operational toil for a small team: structured logging, tracing, monitoring, and incident response tooling that actually works at our scale.

Stack

TypeScript, Cloudflare Workers, Durable Objects, Hono, Drizzle ORM, Postgres, Zod, SST, Vercel AI SDK, Docker, React, Vite.

Who You Are

Minimum

• 5+ years of engineering experience building and operating backend systems in production. You’ve been on‑call.
• Fluent in TypeScript and comfortable working across the stack, but instinctively deeper on the backend.
• Built real‑time systems: WebSockets, SSE, event streaming, or message queues in production.
• Distributed systems intuition, understand consistency tradeoffs, and hold opinions about them.
• Shipped infrastructure to real users, not just internal tooling.

Bonus (but Not Required)

• Worked with Cloudflare Workers, Durable Objects, or serverless compute at the edge.
• Built agent systems, model routing layers, or tool‑use architectures with LLMs.
• Been a founder or early‑stage engineer and care deeply about product.

Compensation & Benefits

Base salary: $180K–$240K + meaningful early‑stage equity + health, dental, 401(k).

The Process

• Application: Submit your resume and answer a few short questions.
• 15‑minute intro call: Quick check to align on location, motivation, and logistics.
• 45‑minute technical interview: Work through a real backend problem.
• System design interview: Deep dive into how you architect systems, using a real Wordware problem.
• Final conversation: Answer your questions and scope the work trial.
• Work trial: Paid trial to work on a real project in person with us, usually a few days to two weeks.

About the company

Wordware (YC S24)