Senior Full Stack AI Engineer

trg.; England; On-site; GBP 90,000 - 140,000; Full time

Benefits offered by this job

Equity

Job summary

trg. is a fast-growing AI startup in the UK, shipping a document-heavy workflow tool for B2B teams. You will own meaningful parts of the product, shaping architecture and direction.

You will build core platform features end-to-end with React, TypeScript, Node, and Python, and drive multi-step agent workflows and evaluation in a hands-on role.

Qualifications

• 4-8+ years of full-stack experience with React, TypeScript, Node and Python.
• Hands-on AI product experience with LangChain and related tooling.
• Experience with context engineering and agent evaluation.
• Ability to own features end-to-end from design to deployment.

Responsibilities

• Build core platform and AI features end-to-end from React frontend to Python backend services.
• Design multi-step agent workflows and context engineering.
• Make key decisions on infra, data models and system design as the platform scales.
• Champion engineering quality through testing, code review, CI/CD and monitoring.
• Collaborate with product, design and customer-facing teams to ship features customers love.

Skills

React

TypeScript

Node.js

Python

Full-stack

Autonomy

Startup experience

LangChain

LangGraph

LangSmith

Tools

CI/CD

Testing frameworks

Job description

I'm working with a fast-growing, VC-backed AI startup that is transforming a document-heavy, high-value workflow for B2B teams. The product is already live with paying customers who report dramatic time savings, and the company is entering a major growth phase.

The team is small and highly focused, and this is a chance to join early, own meaningful parts of the product, and help shape both the architecture and the product direction.

What you'll be doing

• Building core platform and AI features end to end, from polished React frontends to robust Python backend services
• Designing and improving multi-step agentic workflows, including context engineering and agent evaluation
• Making key decisions on infrastructure, data models and system design as the platform scales
• Championing engineering quality through testing, code review, CI/CD and monitoring
• Working directly with product, design and customer-facing teams to ship features customers love

What they're looking for

• 4 - 8+ years of full-stack experience with React, TypeScript, Node and Python
• Hands-on experience building AI products, ideally with LangChain, LangGraph and LangSmith or similar tooling
• Experience with context engineering and evaluating agents
• Comfort owning features from design through to deployment
• Previous startup experience
• Genuine autonomy: you'll largely decide what you work on
• A fast track into senior responsibilities
• Hard, interesting AI problems in a product with proven demand
• Equity in a company with strong momentum