AI Engineer

Annwn; Greater London; Hybrid; GBP 85,000 - 120,000; Full time

Benefits offered by this job

Base salary £85K-£120K

Equity

Hybrid work (up to 2 remote days)

Job summary

Annwn, a sustainability‑tech startup in the UK, is hiring senior/full‑stack AI engineers to build agentic systems at the core of our platform. You will ingest data, reason over domains, run simulations, and support multi-step decision workflows while shaping architecture and collaborating with customers.

Join a mission‑driven team offering meaningful equity, a hybrid work model, and the opportunity to influence early product decisions in a growing company.

Qualifications

• 7+ years building full-stack applications.
• Proficiency in modern web technologies (React/Next.js/TypeScript).
• Experience with backend development using Python.
• Comfort with messy, real-world data.
• Clear communicator who can design, architect, and explain complex systems.
• Use of coding agents to accelerate work (Codex/Claude Code).

Responsibilities

• Ingest and structure unstructured sustainability data.
• Reason across complex, uncertain domains.
• Run simulations and scenario analysis.
• Support multi-step decision-making workflows.
• Improve continuously via feedback and memory.

Skills

Strong software engineering

7+ years full-stack

React/Next.js/TypeScript

Python backend

Messy real-world data

Clear communication

Coding agents (Codex/Claude Code)

Tools

React

Next.js

TypeScript

Python

Job description

About us

We want to make the world a better place. We have worked in sustainability for years and know it is a profession that needs new tools, new ways of working, and can benefit from the latest AI.

We are building an agentic AI & intelligence platform for sustainability action and decision-making.

Organisations today are drowning in fragmented environmental data — carbon, biodiversity, water, policy, supply chains and more — but still struggle to answer the most important questions:

• What should we do next?
• What's the impact if we do?
• What's the return on action — financially and environmentally?

Our startup exists to close that gap. We want to build a dynamic, diverse, positive team. We are big fans of collaboration, new ideas, and chewing over something none of us are quite sure about. We enjoy our work and think it is vital stuff.

We are building a workflow and decision-making layer on top of sustainability data: AI agents that ingest messy real-world inputs, reason over them, run scenarios, recommend actions, and learn from outcomes over time — all while building up a knowledge and context graph to provide the single best view of how the organisation works today.

This is from a team who built a sustainability consultancy from the ground up and successfully exited to one of the largest businesses in the world.

The role

We're looking for Full Stack AI Engineers who want to make a difference and build tech for good reasons. You'll be part of a team building agentic systems from the ground up. You'll work at the core of our platform — designing and implementing AI systems that:

• Ingest and structure unstructured sustainability data
• Reason across complex, uncertain domains
• Run simulations and scenario analysis
• Support multi-step decision-making workflows
• Improve continuously via feedback and memory

You'll have real ownership, real influence on architecture, and direct exposure to customers and real-world sustainability problems.

What we're looking for

We are looking for a positive, collaborative, curious engineer who loves tackling knotty problems. Someone who enjoys learning and applying new knowledge, and who values team contribution.

Research shows that women and people from under-represented groups often only apply to roles when they meet 100% of the criteria. Please don't let that stop you — if you meet most of the skills below and are excited about the mission, we'd genuinely love to hear from you. We strongly encourage applications even if you don't meet every single requirement: we value potential, leadership, and transferable experience, and we're actively working to build a diverse team.

Core skills

• Strong software engineering fundamentals
• 7+ years building full-stack applications
• Proficiency in modern web technologies — ideally React / Next.js / TypeScript
• Experience with backend development using Python
• Comfort working with messy, real-world data
• Clear communicator who can design, architect, and explain complex systems
• Use of coding agents to accelerate work (Codex / Claude Code)

Tech stack & tooling

React, Next.js, TypeScript, Python, Artificial Intelligence, Agentic AI, RAG.

Why join us

We are at a very early stage in our business's life but know how important it is to get the team and the culture right. We know we need lots of different views in the room when we are trying to get to the right solutions, and that support and flexibility are key to getting the best out of everyone. We also strongly believe that the best work comes from a team collaborating and helping each other.

Our work is work that we think really matters — climate, nature, social risk. We believe the latest cutting-edge agentic systems can make a huge difference if we use them well. You'll have strong influence on early key decisions, meaningful equity at an early stage, and work with a passionate team of successful founders.

Logistics

• Base salary: £85K – £120K
• Equity: Competitive
• Employment type: Permanent, full-time
• Remote working: Hybrid (up to 2 remote days per week)
• Visa sponsorship: Not available
• Experience level: Senior, Lead

Interview process

1. 1x screening call (25 mins with CPO)
2. 1x second round interview (workshop-style interview in person at our Farringdon office — we want to simulate you working with us as well as letting you see how you'd work with us)