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 Datacentre 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