Full Stack Engineer

Principal Full Stack Engineer - Azure AI Search & Elasticsearch
6-month contract
Outside IR35
London - 2 days onsite
We are looking for a Principal Full Stack Engineer to lead the design and delivery of enterprise search and AI-driven applications. This is a senior, hands-on contract combining search architecture, full-stack development, Microsoft Azure, DevOps and Generative AI.
Key responsibilities

• Design and optimise enterprise search solutions using Elasticsearch and Azure AI Search.
• Define Elasticsearch cluster architecture, index mappings, aggregation queries and life cycle strategies.
• Improve search relevance, indexing performance, query latency and platform resilience.
• Build Azure AI Search solutions using indexers, custom skillsets, vector search and semantic ranking.
• Develop responsive, search-focused applications using JavaScript/TypeScript and React, Angular or Vue.
• Design and integrate APIs and Back End services across the Azure ecosystem.
• Build enterprise RAG and GenAI solutions using technologies such as LangChain or LlamaIndex.
• Deploy applications using Docker, Kubernetes and AKS.
• Implement CI/CD pipelines through Azure DevOps or GitHub Actions.
• Deliver infrastructure using Terraform or Bicep.
• Provide technical leadership, architectural guidance and engineering best practices.

Essential experience

• At least 10 years of software engineering or solution architecture experience.
• Deep, hands-on Elasticsearch expertise covering cluster architecture, mappings, aggregations, Lucene internals, performance tuning and snapshot/restore.
• Extensive production experience with Azure AI Search, including indexers, custom skillsets, vector search and semantic rankers.
• Strong JavaScript/TypeScript development skills using React, Angular or Vue.
• Experience with Azure Web Apps, Functions, Event Grid, Key Vault, API Management and Private Endpoints.
• Strong Docker, Kubernetes/AKS and CI/CD experience.
• Infrastructure-as-Code experience using Terraform or Bicep.
• Practical experience delivering enterprise GenAI and RAG solutions using LangChain or LlamaIndex.
• Strong communication skills and the ability to influence architectural decisions at principal level.

Relevant Microsoft Azure or Elastic certifications would be advantageous.