Senior AI Frontend Engineer

Sauna•San Francisco, CA

3d•$180,000 - $240,000•Onsite

About The Position

Sauna is a hybrid of AI and software standing on one shared brain. It holds your context and hands you real software built on top of it, so an ordinary Calendly becomes one that writes the invite itself and knows which of your busy hours bend, and for whom. Software for the path you repeat, AI for the edge that never repeats. Wordware is the team behind it, 15 people backed by Spark Capital, Felicis, and Y Combinator with a $30M seed, the largest in YC's history. We build from an office in the Presidio, fifty metres from Crissy Field beach, and we work absurdly hard because we can see and feel the outcome every day. You'll own the frontend of Sauna: shipping interfaces that feel instant, intuitive, and polished even when the underlying work is complex.

Requirements

4+ years of frontend engineering with a portfolio of complex web apps you've shipped.
Portfolio should include multiplayer experiences, apps handling large data with sophisticated fetching and caching, or work with server-sent events (SSE).
Love React and deeply understand state management.
Know when to useMemo, how callbacks work, the component lifecycle, and write beautiful, reusable components.
Recognize when props are being drilled through multiple layers and should be lifted into context or Zustand instead.
Comfortable owning a full-stack feature.
Ability to do the DB migration, write the route in the backend, fetch on the frontend, and create the UI for it.
Product sense and design intuition: ability to take a rough product direction, sketch an interaction, and ship something that feels right.
Care about performance: know when to cache, when to refetch stale data, and how to optimistically update the UI.
Notice duplicated network requests.
Care about the app feeling snappy and responsive.
Make design decisions: own some UX decisions, create simple designs when needed, and unblock yourself.
High autonomy, low ego: do not wait for permission or perfect specs. Ship, gather feedback, and iterate.
Care about craft: details like loading states, empty states, error messages, keyboard shortcuts.
US work authorization.

Nice To Haves

Experience with multiplayer apps (Y.js, Automerge, CRDTs, or similar real-time collaboration frameworks).
Built interfaces for LLM-based tools (streaming responses, handling uncertainty, progressive disclosure).
Experience with local-first architectures (IndexedDB, service workers, sync strategies).
Design background or strong visual sense: ability to make things look good without a designer.
Been a founding frontend engineer and established standards from scratch.

Responsibilities

Make product and design calls yourself.
Prototype quickly.
Execute without waiting for perfect specs.
Implement designs.
Create designs.
Own the frontend of Sauna.
Ship interfaces that feel instant, intuitive, and polished even when the underlying work is complex.