Senior Product Engineer

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 or J-1 visa sponsorship for exceptional candidates.

About the Role

You'll own the product surface of Sauna: the interfaces people use to hand work to it, watch it happen, trust the result, and come back tomorrow.

This is a product role with a frontend center of gravity. You'll follow problems wherever they go: interaction design, client architecture, the API route, the DB migration, the PostHog event that tells us whether it worked. We work quickly. We need someone who can take an idea and turn it into reality: start from a rough direction or a Slack thread, sketch the interaction, ship a first version, and sharpen it from feedback. The PRD and the Figma file, when they exist, come after your first cut.

What You'll Work on

• Delegation primitives: handing work to Sauna, following progress, interrupting, approving, and undoing, for work that runs from seconds to overnight.
• Memory made visible: the surfaces where users see what Sauna has learned about them, correct it, and watch it sharpen from every approval, edit, and rejection.
• Routines and apps: the surfaces where users ask for real software (its own backend, data, and URL), install it, and monitor it and the routines that keep running after the conversation ends.
• Connected Saunas: shared sessions where several people and one Sauna work in the same thread in real time, and the door between one person's Sauna and a colleague's.
• One Sauna, every surface: the same assistant, memory, and identity whether someone opens the web app, texts it from their phone, or @-mentions it in Slack, Superhuman, or email. Includes onboarding that can start from a single text message.
• Performance as a feature: a local-first client (TanStack Query + IndexedDB persistence) that opens instantly on a 10,000-message history.
• First-time experience and billing: the funnel from landing page to trial to paying team, including the parts that make people trust a teammate with their credit card and their inbox.

Who You Are

• You've shipped complex web products and owned them after launch. We want to see the work: multiplayer experiences, large-data apps with real fetching and caching strategy, streaming or realtime UIs.
• You have product taste and act on it. Give you a rough direction and you'll sketch the interaction, build it, and defend the tradeoffs.
• You know React deeply: state management, when to lift into context or a store, what re-renders and why, how to write components other people want to reuse.
• You're comfortable owning a full-stack feature end to end: migration, route, fetch, UI, analytics.
• You care about performance and can explain your caching, invalidation, and optimistic-update choices. Duplicated network requests bother you.
• You care about craft: loading states, empty states, error copy, keyboard shortcuts, the thousand small decisions that make software feel good.
• You use AI heavily in your own workflow and have opinions about where it helps and where it doesn't. Professional AI-product experience is not required, but you're already probing current models and forming views.
• You're autonomous and low ego. You don't wait for a spec, you ship, you get feedback, you iterate. You'd rather own five things fully than touch fifty.

We care about trajectory over tenure. Tell us what you built and how fast you got here.

Stack

TypeScript, React, TanStack (Query, Router, DB), Zustand, TailwindCSS, IndexedDB, WebSockets over Cloudflare Durable Objects, Cloudflare Workers, Postgres (Neon). Fundamentals matter more than a perfect match.

Bonus

• Built UIs for LLM-based products: streaming, uncertainty, progressive disclosure, non-determinism as a design constraint.
• Real-time collaboration (CRDTs, Y.js, Automerge, or a homegrown equivalent).
• Local-first architectures and sync strategies.
• Design background or a strong visual sense; you can make it look good without a designer.
• Founding or early frontend engineer who set standards from scratch.

Compensation and Benefits

Base $180K-$240K + meaningful early-stage equity, health, dental, 401(k), generous PTO, gym budget, lunch. In person at our office in the Presidio, San Francisco.

The Process

Exceptional candidates go from first touch to offer in two weeks.

• Application. Resume, links, and one thing you've shipped that you're proud of. A short demo video or a link to the live thing beats a description.
• 15-minute intro call. Location, motivation, logistics.
• System design interview. We walk through a real Sauna problem together, typically a take-home slide with explicit constraints that you present back.
• Final conversation. Your questions, and we scope the work trial.
• Paid work trial. In person, a few days to two weeks. You own a real feature end to end, present it at Friday week review, and both sides decide.