Contract Full-Stack JavaScript Developer - AI Platform

Contract Full-Stack JavaScript Developer (AI Platform) 📍 Location: 3 days per week in London Office 📆 Duration: 4 weeks with a longer term extension afterwards. 💼 IR35 Status: Outside IR35 💰 Rate: £500p/d – £600p/d Opus is partnering with a cutting-edge FinTech start-up to secure a Contract Full-Stack JavaScript Developer. You’ll be joining a small, high-calibre team building a platform to improve workflows within the the FinTech space. They have a genuinely interesting problem at the intersection of frontend engineering, backend systems, and applied LLM tooling. This is a true 0–1 build, ideal if you enjoy ownership, clean abstractions, and shipping product quickly. 🧠 What You’ll Be Working On Building and extending agent-driven workflows. Developing context management and LLM entry points. Only application-layer LLM integrations, not model training) Expanding slide generation functions and data structures. Full-stack feature development, with a frontend-heavy bias Collaborating closely with product and engineering stakeholders in a fast-moving environment 🛠️ Tech Stack Next.js TypeScript Tailwind CSS Node.js PostgreSQL Claude Agent SDK Pydantic AWS Terraform Modal Sandboxes 📩 Interested? Apply now or send your latest CV to (url removed) ASAP! If you haven’t heard back within 48 hours, please assume your application was not successful this time