Senior AI Frontend Engineer

Sauna•San Francisco, CA

3d•Onsite

About The Position

This is a full-time, in-person role based in San Francisco (Presidio) where employees work from the office 5 days a week. The company is seeking a Senior AI Frontend Engineer to own the frontend of Sauna, shipping interfaces that feel instant, intuitive, and polished even when the underlying work is complex. The role involves making product and design calls, prototyping quickly, and executing without waiting for perfect specifications. The technology stack includes TypeScript, React, Tanstack, Zustand, TailwindCSS, IndexedDB, and Cloudflare Workers. The company, Wordware, is a team of 15 people backed by Spark Capital, Felicis, and Y Combinator with a $30M seed funding.

Requirements

Minimum 4+ years of frontend engineering experience.
Portfolio of complex web apps shipped.
Experience with 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.
Understand useMemo, how callbacks work, and the component lifecycle.
Write beautiful, reusable components.
Recognize when props are being drilled through multiple layers and should be lifted into context or Zustand.
Comfortable owning a full-stack feature.
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.
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 (open to O-1 or J-1 visa sponsorship for exceptional candidates).

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

Own the frontend of Sauna.
Ship interfaces that feel instant, intuitive, and polished.
Make product and design calls independently.
Prototype quickly.
Execute without waiting for perfect specifications.
Implement designs.
Create designs.
Own a full-stack feature, including database migrations, backend routes, frontend fetching, and UI creation.
Make design decisions and create simple designs when needed.
Establish standards from scratch (for founding frontend engineers).