Location: London, United Kingdom (On-site, 5 days/week)
Employment: Full-time
About the Opportunity
An ambitious, well-funded AI startup is looking for its Founding Product Engineer to help build the next generation of AI-powered software from the ground up.
This is a true 0-to-1 opportunity where you'll work directly with the founders to define the product, own major technical decisions, and build customer-facing experiences from concept to production. If you're excited by high ownership, rapid iteration, and using AI as a core part of software development, this role offers the chance to have a lasting impact from day one.
The Role
As the Founding Product Engineer, you'll own the product across the full stack, from frontend interfaces and APIs to AI-powered workflows and developer infrastructure.
This isn't a traditional engineering role. You'll be expected to contribute to product thinking, architecture, customer conversations, and technical strategy while shipping production-ready features at startup speed.
You'll thrive if you enjoy solving difficult technical problems, have strong opinions backed by experience, and prefer building over maintaining.
What You'll Do
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Build and launch product features end-to-end, from idea to production.
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Design scalable APIs and backend systems.
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Develop modern frontend experiences using React and TypeScript.
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Integrate LLMs and AI agents into production workflows.
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Collaborate directly with founders and early customers to shape product direction.
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Make key architectural and product decisions.
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Continuously improve development velocity using AI-powered engineering workflows.
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Help establish the engineering culture and technical foundations of the company.
What We're Looking For
Required Experience:
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6+ years of full-stack software engineering experience (exceptional candidates with fewer years will also be considered).
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Strong expertise in:
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TypeScript
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React
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Node.js
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Experience building products from 0 to 1 in startup environments.
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Hands-on experience integrating LLM APIs (OpenAI, Anthropic, or similar) into production applications.
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Strong product intuition with the ability to balance technical excellence and user needs.
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High level of ownership and autonomy.
Ideal Background:
You'll stand out if you have one or more of the following:
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Experience at a high-performing technology company or AI-focused organization.
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An impressive portfolio of personal projects, open-source contributions, or startup experience.
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Published technical research, conference talks, or notable technical achievements.
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Strong architectural thinking and the ability to influence product direction.
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Excellent communication skills and the ability to work closely with founders.
AI-First Engineering
This team believes AI is fundamentally changing software development.
The ideal candidate already relies heavily on AI coding assistants such as Claude, Copilot, Cursor, or similar tools as a core part of their engineering workflow—not as an occasional productivity boost.
Tech Stack
You'll work across a modern AI-native technology stack including TypeScript, React, Node.js, Rust, Azure, Docker, RESTful API design, AI agents, Large Language Models (LLMs), and full-stack application development. Experience integrating OpenAI, Anthropic, or similar LLM APIs into production environments is highly valued, along with a strong understanding of building scalable, AI-powered products from concept to deployment.
Who You'll Enjoy Working With
You're likely a great fit if you:
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Love building products from scratch.
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Enjoy startup environments where speed matters.
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Think like both an engineer and a product builder.
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Take ownership rather than waiting for tickets.
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Like debating architecture, product decisions, and emerging AI technologies.
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Want to help shape both the product and the company.
Please Note
This is a fully on-site position in London (5 days per week).
Candidates must already have the legal right to work in the UK.
