Founding Engineer

Understanding Recruitment; Greater London; On-site; GBP 90,000 - 150,000; Full time

Job summary

Understanding Recruitment partners with a pre-seed AI startup to find a Founding Engineer in Greater London. This is a rare chance to own early product and shape architecture from day one.

You'll own core loops, tackle real-time LLM UX, and build autonomous systems reliable enough for daily mission-critical work. Expect a fast-paced, founder-style environment with broad responsibilities and tight feedback from users.

Qualifications

• 3–8 years of startup or founding engineer experience.
• Strong mathematical background.
• Generalist mindset with fast shipping.
• Experience shipping in small, elite teams.

Responsibilities

• Work on core agent loops (prompting, tool selection, model choice, memory/context).
• Develop high-performance, real-time LLM-powered UX.
• Ensure autonomous systems are reliable for daily use.

Skills

Frontend tech stack

AI/LLMs awareness

Product thinking

User communication

Full SDLC ownership

Job description

Do you have experience working at an early-stage startup and want to do it again, properly this time?

Are you excited by real ownership, commercial impact, and building something genuinely category-defining?

Experience: 3-8 years (startup / founding engineer background preferred)

We’re partnered with a pre-seed AI startup building agentic AI systems that radically improve how knowledge workers think, decide, and get work done. This is not another chatbot. This is an AI-native product being built from first principles by engineers from elite technical environments (e.g. Palantir, Citadel).

They’re now looking for a Founding Engineer, someone who’s:

• Already been a founding / early engineer or
• Worked in a fast-moving, high-growth startup and understands what it takes to ship real product, fast, with users in mind
• Has a generalist mindset
• A strong mathematical background

You’ll work directly on:

• Core agent loops (prompting, tool selection, model choice, memory & context)
• High-performance, real-time LLM-powered UX
• Making autonomous systems reliable enough for daily, mission-critical work

As a Founding Engineer, you’ll wear many hats:

• Frontend: TypeScript, React
• AI/LLMs everywhere (Cursor/Copilot as a daily workflow)
• Product thinking & UX judgment
• Talking to users and rapidly iterating
• Full SDLC ownership; build, ship, break, fix, repeat

What they’re looking for:

• Strong commercial & product mindset – you care about outcomes, not just code
• Comfortable in ambiguity and zero-to-one environments
• Proven ability to ship fast in small teams
• AI-native way of working (LLMs are tools, not toys)
• Resilient, adaptable, and genuinely excited by hard problems
• Real ownership — technical and product
• Small, elite team that ships fast
• Well-founded with long runway
• You’ll help define a product shaping the next generation of software
• Not another boring B2B Saas… this is something you’d actually use