Lead Full Stack Engineer

Location: City of Westminster

LEAD FULLSTACK SOFTWARE ENGINEER

12 month Contract
2-3 days per week in Westminster, London
£650 - £700 per day inside IR35

TXP are looking for a Lead Fullstack Software Engineer to join our clients team. Working alongside existing developers, tech leads, and the platform group. This is application and service-level work, not infrastructure at the network or hardware layer. The separate Platform Engineering team owns the underlying cloud infrastructure, networking, and shared platform services; this role operates at the application layer, consuming and collaborating with the platform rather than owning it.

Responsibilities

Lead the migration of services off the London Data centre onto AWS and Kubernetes, with .NET 10 as the target runtime
Build and maintain shared service templates, libraries, and patterns so the wider team can converge on a consistent, modern estate
Design and build migration pipelines that combine Terraform, CI/CD, and AI coding agents to refactor and move services at scale, including adding test coverage as part of the migration step
Work with the platform team on observability, networking, and dependency management as services land in the cloud estate

Required Experience

Strong C# and .NET development experience (at least 8 years), including modern .NET and familiarity with the .NET Framework constraints typical of legacy estates
Hands-on AWS experience, building g, deploying, and operating production workloads
Production experience with Kubernetes, including deploying and operating workloads on K8s in a cloud environment
Strong Terraform skills and a track record of using infrastructure-as-code to provision and manage cloud environments
Comfortable working through authentication issues across a mixed estate, including handling legacy mechanisms and bringing services onto modern, token-based patterns

Experience with SQL Server
Active day-to-day use of agentic coding tools such as Claude Code, Codex, or equivalent, with a willingness to drive substantial refactors and migrations through them rather than by hand

Desireable Experience

Python development for tooling, automation, and pipeline work
Experience leading large legacy-to-cloud migrations, particularly off on-prem Windows estates
Experience designing service templates or "golden paths" that other engineers adopt and build on
Familiarity with observability tooling, including metrics, tracing, and structured logging across distributed services