Senior Python AI Engineer
WTW · London
Ready to build production AI that actually ships — not another proof-of-concept chatbot?
Join us as a Senior Python AI Engineer on HR Expert, where you'll help design and build a modern, AI-enabled application from the inside out. This is a genuinely hands-on engineering role at the cutting edge of generative AI, agentic systems and Retrieval-Augmented Generation (RAG) — solving the hard, interesting problems around AI orchestration, information retrieval and grounding that most engineers only get to read about.
With strong Python at the heart of everything you do, you'll work across a modern AI stack — LangGraph, LangChain, FastAPI, Azure, vector search and graph databases — building sophisticated, reliable systems that scale. You'll join a talented, multidisciplinary team that values engineering craft as much as innovation, and any wider full-stack or .NET background you bring will be a real bonus. If you've already built LLM-based applications and you're itching to take them to the next level of sophistication, reliability and scale, this is your chance to shape how AI is genuinely used in enterprise software.
Beyond the tech, we're looking for someone who enjoys solving challenging problems, can take them from design through to production, communicates clearly with technical and non-technical stakeholders, and takes ownership of the quality and reliability of their work.
Come and help us define what great enterprise AI looks like.
The Role
- Design, develop and maintain AI-powered application services using Python.
- Build and evolve agentic workflows and AI orchestration using LangGraph and LangChain.
- Develop scalable APIs and backend services using FastAPI.
- Design and implement Retrieval-Augmented Generation (RAG) pipelines that combine LLMs with enterprise knowledge and data sources.
- Work on retrieval strategies including vector, metadata and graph-based retrieval.
- Contribute to the architecture and implementation of complex AI workflows involving multiple agents, tools and data sources.
- Integrate AI services with the wider HR Expert application and existing enterprise systems.
- Develop and deploy solutions using Microsoft Azure, working across relational, document, vector and graph-based data stores.
- Collaborate with architects, developers, product owners and other technical specialists to turn requirements into robust technical solutions.
- Participate in technical design discussions, code reviews and engineering decision-making.
- Help establish good engineering practices around testing, observability, performance and maintainability of AI applications.
- Investigate emerging AI technologies and evaluate where they can provide practical value to the product.
- Occasionally contribute to frontend or existing .NET services where needed — though this is not the primary focus of the role.