Senior Full-Stack Engineer - TypeScript (AI and LLM Integration) -

Senior Full-Stack Engineer (TypeScript & LLM Integration)

£80-110K + Equity

A hugely exciting AI start-up is seeking several experienced Full-Stack Engineers to join a dynamic product team, focused on building innovative software powered by cutting-edge AI technologies.

This is a unique opportunity for a passionate developer to contribute to an ambitious product and work at the forefront of AI integration.

About the Role

The successful candidate will work within a unified codebase that powers both the B2B software platform and its custom AI capabilities. Responsibilities will span the full feature lifecycle, from design (including data structures) to AI integration, enhancing user experiences through advanced Large Language Models.

Key Responsibilities

Build and maintain web application features using TypeScript, React, Node + Next.js

Contribute to and maintain a monorepo that includes both the B2B SaaS platform and AI/LLM modules

Integrate and optimize commercially available LLMs (e.g., OpenAI, Gemini) via prompt engineering and inference pipeline management

Implement multi-step LLM workflows using orchestration frameworks such as LangChain.

Design and optimize the MySQL database

Develop and maintain type-safe RPC endpoints using tRPC and TypeScript to ensure smooth frontend-backend communication

Rapidly onboard to a modern TypeScript stack to support high-velocity feature development

Required Qualifications

Proven experience working in a unified codebase combining application logic and AI/LLM components

Strong proficiency in building modern web applications with Next.js, tRPC, TypeScript, and Prisma

Practical experience integrating with AI models such as ChatGPT or Gemini, including prompt engineering and API management

Familiarity with tools like LangChain (or similar) to implement multi-step AI workflows

A demonstrated ability to learn quickly and deliver functional features in a fast-paced environment

Preferred Qualifications

Experience deploying and fine-tuning custom AI models

Prior experience developing B2B software platforms with multi-user functionality