Founding Product Engineer

Location: London, United Kingdom (On-site, 5 days/week) Employment: Full-time About the OpportunityAn 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:TypeScriptReactNode.jsExperience 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. Fill in the form, we will contact you...