Job Title
Founding Frontend Engineer
Salary
Not Disclosed
Company Description
Mozart AI is a $7M+ funded London startup backed by Balderton Capital and Kevin Hartz, transforming music creation into a social, effortless experience. We are building the future of music production with a WASM audio engine and real-time collaboration tools for everyone from grandmas to Grammy winners.
Job Description
As the Founding Frontend Engineer, you will own the "backend of the frontend" for a million-line React codebase. You'll architect high-performance SSR systems, scale state management, and build agent-ready UI infrastructure. This is a high-ownership role for a specialist-generalist who values velocity, product taste, and defining the future of music.
Location
London, UK
Why this role is remarkable
- Work directly with the founders to own the end-to-end architecture, state, and delivery for a revolutionary social music product.
- Backed by $7M+ from elite investors including Balderton Capital (backers of Revolut) and Kevin Hartz (founder of Eventbrite).
- Tackle extreme engineering challenges like a WASM audio engine, 60fps WebGL rendering, and real-time multiplayer collaboration.
What You Will Do
- Master the 1M+ line React codebase to own the TanStack Start and SSR architecture, streaming, and caching strategies.
- Consolidate client state management and harden UI/state separation to ensure a thin, predictable wrapper over backend APIs.
- Build agent-native infrastructure, ensuring all UI actions are accessible to AI agents through decorators and semantic code paths.
The ideal candidate
- Deep React expertise with production SSR experience and a proven ability to architect large-scale, high-performance web applications.
- AI-native workflow where agents are your primary tool for refactors and building automated verification systems and E2E tests.
- Strong product taste with an interest in music creation and the ability to work in-office 5 days a week in London.
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Founding Frontend Engineer (+ Equity) at Mozart AI in London employer: Jack & Jill
At Jack & Jill, we pride ourselves on being an exceptional employer that fosters a dynamic and innovative work culture. Our team enjoys a range of benefits including flexible working arrangements, professional development opportunities, and a collaborative environment that encourages creativity and growth. Located in a vibrant area, we offer unique advantages such as access to cutting-edge technology and the chance to work with industry leaders in AI-driven marketing strategies.
