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