Fullstack Engineer - AI

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