Senior Python AI Engineer - Production-Grade LLMs & RAG

Aimlroles; Greater London; Hybrid; GBP 110,000 - 150,000; Full time

Benefits offered by this job

Hybrid work options

Private healthcare

Volunteer day

Job summary

WTW in London is seeking a Senior Python AI Engineer to design and build production AI-enabled services. You’ll work on generative AI, agentic systems and RAG, solving real orchestration and grounding problems at enterprise scale.

Strong Python, LangGraph/LangChain, FastAPI and Azure experience required. You’ll implement scalable APIs, AI workflows, and integration with enterprise data stores, collaborating with architects and product teams to ship reliable AI applications.

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.
• 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.

Skills

Python production

APIs & backend

LLMs

LangChain

LangGraph

RAG pipelines

REST APIs

CI/CD testing

Tools

FastAPI

Azure

vector search

graph databases

ArangoDB

Docker

Kubernetes

Angular

NgRx

.NET / C#

Job description

WTW in London is seeking a Senior Python AI Engineer to design and build production AI-enabled services. You’ll work on generative AI, agentic systems and RAG, solving real orchestration and grounding problems at enterprise scale.

Strong Python, LangGraph/LangChain, FastAPI and Azure experience required. You’ll implement scalable APIs, AI workflows, and integration with enterprise data stores, collaborating with architects and product teams to ship reliable AI applications.