Founding Engineer Jobs in California

Want to own an app that 150k+ musicians already use, and create the next one from zero?

A seed-funded AI music startup in the Bay Area cracked one of the hardest problems in music tech: turning audio into accurate notation. Drop in any recording or video link and receive notation in the format you need: sheet music, tabs, MIDI, MusicXML or a piano roll you can interact with. It covers nine instruments. Their other iOS app teaches you a song note by note on a piano roll, with instant feedback while you play. Growth runs at 60% a month across 150 countries, without spending a dollar on marketing. $5M seed raised.

Right now mobile means iOS only, and there's no one else working on it. You take over the entire mobile codebase: iOS first, Android after. Step one: bringing transcription to mobile. Step two: a brand-new, AI-native learning app built on their own models.

This is a product-leaning full-stack seat. You can handle the backend on your own, but design and product instinct count most. People hold this product in their hands, so the haptics and the feel must be spot on. Your taste, your pace and your product sense count for more than years of Swift.

What you'll own

• The complete mobile codebase from day one, starting on iOS and adding Android
• The foundations: data model and database, auth, payments
• Getting from spec and mockup to production at high speed, then refining based on user feedback and usage data
• The whole mobile experience, down to the haptics and the small details that make an app feel nice
• Over time: mentoring junior devs and setting the mobile engineering culture

What you bring

• A full-stack mobile developer who leans toward product: you can run the backend alone, but frontend and product are where you shine
• Mobile: React Native, Swift, Kotlin or comparable. Web: Next.js, Tailwind. Backend: a BaaS, ideally Supabase. Plus auth, payments, data modeling and APIs.
• Enough depth to coach others and to know when to go fast and when to build it properly
• Strong design and product instinct; you ship fast and push back constructively
• A first-principles thinker who owns the app without hand-holding
• 0–4 years. Your portfolio matters more than your years: 1–2 years is the sweet spot, and less is fine if what you've built is impressive
• You keep up with current best practices and use AI tools every day

Bonus points

• You play an instrument or simply love music, at any level
• MIDI or MusicXML experience
• Game development or learning software
• Consumer apps with visible polish
• A multidisciplinary background

What's in it for you

• $120k–$200k base
• Full ownership of a product musicians use every day, and the chance to build the next one
• Visa sponsorship available (a good part of the team is on visas)

Good to know

• Full-time, in person in the SF Bay Area, 9-9-5. Weekend work happens only in emergencies.
Process: intro call with the CTO take-home UX/UI build ("build this, make it nice") product interview technical interview (live coding or system design; how you think beats how hard it is) conversation with the team final call with the CEO
• offer

Does this sound like you? Apply now. If you're a match, we'll be in touch within 3 working days.

RnB Consultancy | Netherlands | 3604 AB Maarssen | KvK 71489703