Senior React Developer

We are looking for a Frontend Developer for an early-stage AI startup building a product - a personal AI assistant designed for knowledge workers. Our system understands user context, prioritizes work, operates in the background, and delivers supervision-ready output instead of waiting for prompts. We are a small, high-agency team building a product that demands craft, speed, and ownership.This is a foundational hire. You will own the entire frontend and shape the user experience of a complex AI-driven application. You will ship polished, intuitive, and high-performance interfaces. This is not a role where you wait for pixel-perfect designs. You will make product and design decisions independently, prototype quickly, and execute without perfect specs.Craft matters. Loading states, empty states, keyboard shortcuts, performance optimizations, and UX details are expected to feel deliberate and refined.Location: San Francisco, CA (On-site)Employment: Full-timeLevel: SeniorStart: ASAPMust be US-based or willing to relocate before startingUS work authorization or O-1 eligibility requiredTech StackTypeScript, React, TanStack, Zustand, TailwindCSS, IndexedDB, Cloudflare Workers.What You’ll DoOwn frontend architecture and feature development end-to-endBuild complex, production-grade React applicationsMake product and interaction design decisions when neededRapidly prototype and iterate based on feedbackEnsure performance, scalability, and maintainabilityOccasionally handle lightweight backend tasks when requiredEstablish frontend standards and best practicesWhat We’re Looking For4+ years of frontend engineering experienceDeep expertise in React and TypeScriptStrong understanding of state management and performance optimizationPortfolio of complex web applications used in productionAbility to own features end-to-end (from backend adjustments to UI/UX)Strong product sense and design intuitionHigh autonomy, ownership mindset, low egoComfortable operating without detailed specificationsWithout a strong portfolio and clear product-oriented thinking, the process will not move forward.Nice to HaveExperience with multiplayer apps (CRDTs, Y.js, Automerge)Experience building LLM-based interfaces (streaming responses, progressive disclosure)Local-first architectures (IndexedDB, service workers)Design background or strong visual senseExperience as a founding frontend engineerInterview ProcessApplication (resume + short questions)1-minute Loom introduction15-minute intro callSystem design interviewFinal conversationPaid in-person work trialBenefitsMeaningful early-stage equityHealth and dental coverage401(k)Generous PTOGym budget and daily lunch