Senior Full-Stack Engineer (TypeScript & LLM Integration) - £110K, Remote UK (United Kingdom)

Senior Full-Stack Engineer (TypeScript & LLM Integration) £80-110K + EquityA 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 RoleThe 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 ResponsibilitiesBuild and maintain web application features using TypeScript, React, Node + Next.jsContribute to and maintain a monorepo that includes both the B2B SaaS platform and AI/LLM modulesIntegrate and optimize commercially available LLMs (e.g., OpenAI, Gemini) via prompt engineering and inference pipeline managementImplement multi-step LLM workflows using orchestration frameworks such as LangChain.Design and optimize the MySQL databaseDevelop and maintain type-safe RPC endpoints using tRPC and TypeScript to ensure smooth frontend-backend communicationRapidly onboard to a modern TypeScript stack to support high-velocity feature developmentRequired QualificationsProven experience working in a unified codebase combining application logic and AI/LLM componentsStrong proficiency in building modern web applications with Next.js, tRPC, TypeScript, and PrismaPractical experience integrating with AI models such as ChatGPT or Gemini, including prompt engineering and API managementFamiliarity with tools like LangChain (or similar) to implement multi-step AI workflowsA demonstrated ability to learn quickly and deliver functional features in a fast-paced environmentPreferred QualificationsExperience deploying and fine-tuning custom AI modelsPrior experience developing B2B software platforms with multi-user functionality