Join a high-velocity team of four engineers building the "Duolingo for anything." As a Staff-level individual contributor, you will own the technical foundation of a platform serving 1.7M monthly users. Reporting to the CTO, you'll scale backend systems and design features like spaced repetition to help a billion people learn through gamification.
Back to all jobs
Find a job with Jack
This job is no longer actively hiring. Open Roles to see active jobs.
Staff Fullstack Product Engineer at Gizmo
Join Gizmo.ai, the UK startup building the 'Duolingo for anything,' as a Staff Fullstack Product Engineer. With $5M ARR, 1.7M monthly users, and a fresh $22M Series A, this is a rare chance to be a core member of a tiny, elite engineering team. Reporting to the CTO, you'll own the backend systems and gamification features that make learning addictive for millions. If you have a builder's DNA and want to help a billion people learn, this London-based hybrid role offers massive impact and early-stage equity in one of the UK’s fastest-growing AI companies.
About this role
Role overview
About the company
Gizmo
Software
Gizmo.ai - AI-powered learning platform backed by $22M Series A
What you'll do
What you will do
- Design and scale the high-performance backend services and APIs that power the core learning experience across web and mobile platforms.
- Integrate advanced product capabilities including AI-driven personalization, social mechanics, and spaced repetition algorithms to drive user engagement.
- Collaborate across the full stack to ship seamless features, supporting frontend codebases and technical planning to maintain high engineering standards.
Who you are
Who this is a fit for
- Expert-level fullstack fundamentals with a heavy backend focus and a proven track record of shipping complex, consumer-facing product features.
- Strong proficiency in SQL and experience with Python or TypeScript; you are comfortable standardizing a growing stack on TypeScript and modern infrastructure.
- A "maker" mindset with previous startup or founding experience, driven by moving the needle on business-critical metrics and user impact.
Why this role
Why this role is remarkable
- Massive scale and traction: You will be one of the earliest employees at a startup already generating $5M ARR with 1.7 million monthly active users.
- Significant capital backing: Influence the future of education with the resources of a recent $22M Series A round from top-tier leading investors.
- Founding-level autonomy: Work directly with the Co-Founder/CTO in a flat structure where you own features from architectural concept to production deployment.
Jack & Jill
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
I recruit from Jack’s network and make the intro when I spot a great match.And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.
Meet Jack
Jack gets to know what you're great at and what you want next, then searches 15 million jobs daily and helps you discover roles at companies like this.
How does this work?
Tell Jack what you want
He learns what great work looks like for you, then scans 15M jobs every night to find your best matches.
Reply to refine your search
React to roles in-app or by email. Jack adjusts, tracks applications, and keeps improving the more you share.
Land the role
Mock interviews, salary benchmarking, and coaching calls. Free for candidates.