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Engineering · Senior

Back-end Developer

Build the AI backbones: RAG systems, agent workflows, production inference services, evaluation suites.

Remote (UK)
Full-time, permanent

About the role

You will own the backend of our client AI integrations. RAG systems, agent workflows, evaluation suites, and production deployments into client environments. You will choose the right architecture, ship it in 4 to 8 weeks, and write handoff docs clear enough that client teams can own it after we leave.

AI-first spec

How AI fits into this role.

Every project starts with "what is the right AI architecture", not "what is the CRUD model". You will choose between RAG and fine-tuning, build evaluation suites that actually catch regressions, ship to production, and own the feedback loop. Claude writes your first draft of most code. You will be using agent frameworks (LangGraph, Mastra, or Claude Code Agent SDK) for real production workloads, not demos.

Tools you'll use daily

  • Claude (pair programming and architecture decisions)
  • Python with FastAPI or TypeScript with Hono
  • PGVector, Pinecone, or Qdrant
  • LangGraph or Mastra for agents
  • LangSmith or Phoenix for evaluations

What you'll do

  • Design and ship RAG systems, agent workflows, and LLM-powered APIs
  • Integrate with client data sources (warehouses, document stores, third-party APIs)
  • Build evaluation suites that catch regressions before they reach production
  • Ship to production in client environments (AWS, GCP, Azure, on-prem)
  • Write clear handoff documentation so clients can run the system after we leave
  • Help clients choose the right tool for the problem, not whatever is trending

What we're looking for

  • 4+ years shipping production backend systems
  • Strong Python or TypeScript / Node.js for API development
  • Production experience with at least one LLM provider (OpenAI, Anthropic, open source)
  • Database and data pipeline experience (Postgres, vector databases, ETL)
  • Based in the UK, eligible to work without sponsorship

Nice to have

  • RAG or embeddings production experience
  • Agent frameworks (LangGraph, Mastra, Claude Code Agent SDK)
  • Evaluation and observability tools (LangSmith, Phoenix, Braintrust)
  • Fine-tuning experience (LoRA, SFT)
  • Experience in regulated industries (fintech, healthtech, legaltech)

Ready to apply?

Drop us your CV and a short cover note. We read every application and reply within one working day.