Founding Product Engineer (AI-First)

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

• Build and launch product features end-to-end, from idea to production.
• Design scalable APIs and backend systems.
• Develop modern frontend experiences using React and TypeScript.
• Integrate LLMs and AI agents into production workflows.
• Collaborate directly with founders and early customers to shape product direction.
• Make key architectural and product decisions.
• Continuously improve development velocity using AI-powered engineering workflows.
• Help establish the engineering culture and technical foundations of the company.

What We're Looking For

Required Experience:

• 6+ years of full-stack software engineering experience (exceptional candidates with fewer years will also be considered).

Strong expertise in:

• TypeScript
• React
• Node.js

• Experience building products from 0 to 1 in startup environments.
• Hands-on experience integrating LLM APIs (OpenAI, Anthropic, or similar) into production applications.
• Strong product intuition with the ability to balance technical excellence and user needs.
• High level of ownership and autonomy.

Ideal Background:

You'll stand out if you have one or more of the following:

• Experience at a high-performing technology company or AI-focused organization.
• An impressive portfolio of personal projects, open-source contributions, or startup experience.
• Published technical research, conference talks, or notable technical achievements.
• Strong architectural thinking and the ability to influence product direction.
• 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:

• Love building products from scratch.
• Enjoy startup environments where speed matters.
• Think like both an engineer and a product builder.
• Take ownership rather than waiting for tickets.
• Like debating architecture, product decisions, and emerging AI technologies.
• 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.