Mid-Senior Founding Full-Stack Product Engineer | London, On-site in Southampton

Our Client is building the world's first AI‑native cybersecurity operating system. As increasingly capable AI systems become part of critical infrastructure, security challenges are evolving faster than traditional solutions can keep up. Our Client is developing next‑generation defensive systems powered by AI‑native architectures, advanced research, and novel approaches including LLM Zero Knowledge Verifiers (ZKVs). Backed by leading investors including Entrepreneur First and the Sequoia Scout Fund, alongside strategic angels from companies such as Meta, Palantir, Isomorphic Labs, Asana, Samsara, and Astranis, the company is building from offices in London and San Francisco.

Location: London, United Kingdom (On‑site)

Employment Type: Full‑Time

Level: Mid‑Senior

Compensation: Competitive Salary + Founding Equity

Relocation Support: Available for Candidates with Work Permit

What You’ll Do

• Own the product end‑to‑end; build and maintain the full product experience.
• Develop frontend, backend, and AI‑powered workflows.
• Design scalable, secure, and reliable systems.
• Shape product architecture and engineering standards.

Full‑Stack Development

• Build modern web applications using TypeScript and React.
• Develop backend services using Node.js.
• Design and maintain developer‑friendly APIs.
• Ensure security, performance, and reliability across the platform.

AI Product Development

• Collaborate closely with AI engineers.
• Integrate AI and LLM capabilities into production products.
• Transform research outputs into customer‑facing functionality.
• Explore how AI‑generated code and autonomous systems fit into enterprise environments.

Enterprise Platform Engineering

• Build secure systems suitable for enterprise deployment.
• Support compliance and security requirements.
• Improve platform scalability and reliability.
• Design infrastructure capable of supporting long‑term growth.

Requirements

• Strong full‑stack engineering experience.
• Deep expertise with TypeScript, React, and Node.js.
• Experience designing and building RESTful APIs.
• Experience shipping production‑grade software.
• Strong architectural and product thinking.
• Experience working in fast‑moving startup environments.
• Comfort operating with significant ownership and autonomy.

Preferred Experience

• AI or LLM product integrations.
• OpenAI, Anthropic, or similar production AI systems.
• Cybersecurity or enterprise SaaS environments.
• Cloud infrastructure experience (Azure, AWS, or GCP).
• Docker and containerized deployments.
• CI/CD pipelines and GitHub Actions.
• Terraform or Infrastructure as Code.
• Rust experience.
• Previous founding engineer experience.

Ideal Candidate Profile

• Think like product owners.
• Use AI tools extensively in their development workflow.
• Have strong opinions on architecture and software design.
• Enjoy working directly with customers and founders.
• Thrive in high‑ownership environments.
• Prefer building over maintaining.
• Move quickly while maintaining quality.

What We Offer

• Competitive compensation package.
• Meaningful founding equity.
• Direct access to founders and leadership.
• High‑impact ownership from day one.
• Opportunity to work on cutting‑edge AI and cybersecurity problems.
• Fast‑moving, high‑performance environment.
• Ability to influence both product and technical strategy.

How to Apply

If you are excited about building AI‑native cybersecurity products, owning systems end‑to‑end, and helping define the future of AI security infrastructure, we would love to hear from you.