Founding Product Engineer

Mozart AI; Greater London; On-site; GBP 90,000 - 150,000; Full time

Job summary

Mozart AI is seeking a founder-level builder to own our next big product. You’ll work directly with the CEO to uncover demand, then design, code, and ship a hit that people return to daily. This role demands hands-on ownership, rapid experimentation, and a relentless focus on retention.

You’ll be measured by product-market fit, growth signals, and the speed at which you convert bets into real users. This is an intense, in-person role in London for a creator who wants to ship something lasting.

Qualifications

• Built and shipped consumer products people loved.
• Ship things that look and feel great without a designer.
• Know how consumer products grow: channels, loops and virality.

Responsibilities

• Find the next hit by turning ideas into sharp bets.
• Prove demand before building with ads, landing pages, prototypes.
• Build end-to-end: design, code, and ship to real users quickly.
• Acquire users yourself with ads, creatives, and channels.
• Measure retention daily and focus on day-30 metrics.
• Iterate fast or kill initiatives when signals fade.
• Work directly with the CEO and own the outcome.

Skills

Builder

Design taste

Consumer growth

Retention literacy

Writes code

Low ego

High ownership

Job description

Mozart AI is music's first creation network, where the world goes from listening to music, to making it together, to being known for it. 1.5 billion people can play an instrument. We're building the products that turn them into artists, and turn their fans into the next ones. Our customers love us, and include everyone from grandmas using Vibe sessions to Grammy winners using the Studio. Music is having its first explosive moment of creation-driven consumption, and we aspire to shape that world to preserve the social and fun elements of music creation.

We've raised over $7M from Balderton Capital (backers of Revolut) and several Silicon Valley legends like Kevin Hartz and Emery Wells, who have backed companies like Uber, Spotify, Reddit, and other massive consumer outcomes.

We're a small, talent-dense team building the future of music from our London office. We operate with high ownership, high velocity, and low-ego collaboration — specialist generalists who work hard, learn fast, and ship relentlessly. We care deeply, move fast, and we're here to build something that outlives us.

About the Role

• You'll be the founder of our next big product. Working directly with the CEO, you'll find new ways for people to make and listen to music together that they come back to every day. You'll prove demand before writing a line of code, then build it, ship it, and grow it yourself. No PM, no handoffs, no waiting on another team.
• This is an intense, in-person role for builders who want to find a hit, and who want to be judged on one thing: whether people keep coming back.

What You'll Do

• Find the next hit. Turn ideas for how people create and listen to music together into sharp bets
• Prove demand before you build. Test every bet with ads, landing pages, prototypes, etc, and only build what people actually reach for.
• Build it yourself, end to end. Design it, write the code across the stack, and put it in front of real users in days.
• Bring your own users. Make the ads, creatives, and channels that put people into your product, without waiting on growth or engineering.
• Measure from day one. Obsess over retention, L30, and anything that indicates “f*ck yea, this really works”.
• Iterate until it works, or kill it. Read retention daily, fix what's broken, and make the call fast: double down when the signal is there, move on when it isn't.
• Work directly with the CEO.

What We're Looking For

• Builder. You have built and shipped consumer products that people genuinely loved, ideally your own.
• Design taste. You ship things that look and feel great without waiting for a designer.
• Consumer growth. You know how consumer products actually grow: channels, loops, sharing, and virality, and you've run your own ads.
• Retention literacy. You read D1, D7, D30, and L30 curves fluently, know what great looks like, and know what to change when a curve is wrong.
• Writes code. You build full stack on your own and ship to production.
• High ownership, low ego. You ship fast, own outcomes after release, and do whatever needs doing.

Nice-To-Haves

• You have founded a company
• You have launched a consumer product that took off on social
• Real-time, social, or creative consumer products