Founding Engineer

Understanding Recruitment; England; On-site; GBP 90,000 - 130,000; Full time

Job summary

Understanding Recruitment partners with a pre-seed AI startup to hire a Founding Engineer who has been a founding/early engineer or worked in fast-growth startups. You'll own core agent loops and build real-time LLM-powered UX.

You'll wear many hats including frontend with TypeScript/React, AI/LLMs as daily workflow, product thinking, talking to users, and end-to-end SDLC ownership. If you thrive in ambiguity and want to shape the next generation of software, this is for you.

Qualifications

• 3-8 years' experience as founding/early engineer in a startup.
• Generalist with product focus and ownership.
• Strong mathematical background.

Responsibilities

• Develop core agent loops (prompting, tool selection, memory context).
• Build high-performance, real-time LLM-powered UX.
• Ensure autonomous systems are reliable for daily use.
• Own full SDLC from design to release and iteration.
• Talk to users and iterate quickly.

Skills

TypeScript

React

AI/LLMs

Product thinking

Generalist mindset

Mathematics

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:

• 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-funded 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

If you're ready to step into a true founding-level role, influence the product direction, and build something genuinely new, this is the one. Interested?