Senior Python AI Engineer - Hybrid, Scalable LLM Pipelines

WTW; Greater London; Hybrid; GBP 90,000 - 140,000; Full time

Benefits offered by this job

Hybrid work options

Private healthcare

Life insurance

Pension with matched contributions up

Volunteer day

Share scheme

Electric vehicle car scheme

Job summary

WTW is seeking a Senior Python AI Engineer in the London area to design and build AI-enabled enterprise services. You will craft AI-powered backends, orchestration workflows, and scalable APIs using FastAPI, LangGraph and LangChain, delivering robust RAG pipelines and reliable production systems.

You’ll collaborate with architects and product owners, contribute to testing, observability and performance improvements, and explore cutting-edge AI tech for enterprise use.

Qualifications

• Strong Python development experience in production applications.
• Experience building APIs and backend services, ideally with FastAPI.
• Proven experience building applications with LLMs, using LangChain and/or LangGraph and agentic workflows.
• Experience developing RAG solutions and integrating multiple systems and data sources via REST APIs.
• Solid engineering practices — automated testing, source control, code review and CI/CD — with a focus on production-quality software over prototypes.
• A good understanding of production generative AI challenges: retrieval quality, grounding, context management, evaluation, reliability and performance.

Responsibilities

• 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.
• 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.

Skills

Python

APIs

FastAPI

LangChain

LangGraph

LLMs

RAG

Azure

Docker

Kubernetes

CI/CD

Tools

LangGraph

LangChain

Azure AI

Cosmos DB

Job description

WTW is seeking a Senior Python AI Engineer in the London area to design and build AI-enabled enterprise services. You will craft AI-powered backends, orchestration workflows, and scalable APIs using FastAPI, LangGraph and LangChain, delivering robust RAG pipelines and reliable production systems.

You’ll collaborate with architects and product owners, contribute to testing, observability and performance improvements, and explore cutting-edge AI tech for enterprise use.