Contract Full Stack Engineer – Next.js & AI Systems (Remote EU)

We’re supporting a fast-growing AI product team who are looking for a Contract Full Stack Engineer to help them take an early-stage platform from prototype through to a scalable, production-ready MVP.

The product is already up and running with a working UI, design system and initial architecture in place. The next phase is all about scaling the system properly, particularly across backend architecture, AI agent workflows, and evaluation/feedback loops.


What you’ll be working on
  • Building and extending features in a Next.js-based application
  • Helping define and evolve backend and system architecture
  • Designing and improving AI agent workflows and orchestration
  • Building evaluation frameworks, feedback loops, and quality measurement for LLM outputs
  • Supporting the transition from prototype to scalable MVP
  • Working closely with product and engineering stakeholders day-to-day
Tech stack
  • React/Next.js
  • Postgres / Supabase
  • Arize Phoenix
  • Flexible backend approach (still being shaped)
What we’re looking for:
  • Strong Full Stack engineering experience in production environments
  • Hands-on experience with AI-enabled products, LLM workflows, or agent-based systems
  • Familiarity with evaluation, prompt testing, or LLM quality measurement is important
  • Exposure to LangGraph, Langfuse, and LangSmith would be highly relevant
  • Experience with MCP-style infrastructure or tool orchestration patterns (e.g. caching/retrieval layers such as mcp-refcache) 
  • Comfortable working in fast-moving, product-led environments
  • Experience working in AI-native setups (e.g. using tools like Claude Code) is a plus
There is a strong alignment with candidates who have worked across the LangGraph / Langfuse / LangSmith ecosystem. Experience building or contributing to MCP-style infrastructure patterns is particularly relevant given the direction of the platform.

Contract details:
  • 3-month contract
  • Remote (EU-based)
  • Occasional fully expensed travel for in-person collaboration sessions