Back End Developer

London | Hybrid | Outside IR35 | 6-month initial contract

Are you a Senior Backend Engineer with strong TypeScript, C# and AI-assisted development experience, looking for the opportunity to work on something genuinely new?

Our client is building a new digital delivery platform and is looking for a Senior Backend Engineer to join a small, high-performing engineering team.

This is a contract position, initially for 6 months with potential for extension. The role is outside IR35, based in London on a hybrid basis, and the client is looking for someone to start as soon as possible.

This is a TypeScript-forward backend role , with genuine hands-on C#/.NET work. The successful engineer will build new services and BFF endpoints in TypeScript, whilst also working with existing C#/.NET services to understand and faithfully port established business logic into the new platform.

A key part of the role will be agentic development , using AI coding tools such as Claude Code as part of the day-to-day engineering workflow. They are looking for someone who is comfortable working with AI-generated code, reviewing it critically and helping to improve the standards and tooling used across the team.

What they’re looking for:

• Strong Senior-level TypeScript/Node.js experience, particularly building APIs and BFFs
• Solid hands-on C#/.NET 8+ experience, with the ability to understand and port existing services and business logic
• Strong experience with REST and GraphQL APIs , contract-first development, schemas and mocks
• Experience with OpenSearch or Elasticsearch , including query design and index modelling
• Good understanding of message-driven architectures , including queues, retries and idempotency
• Demonstrable, hands-on use of AI coding tools , ideally Claude Code, as part of the development workflow
• Experience working with microservices and distributed systems
• AWS experience is desirable, particularly IAM, SQS and managed services
• Experience with Redis, feature flags or configuration services would be beneficial

The ideal candidate will be a strong, hands-on engineer who enjoys working in a small, collaborative team, is comfortable working autonomously and has a high standard for code quality. They should also be happy working with existing and legacy systems, taking the time to understand how they work before porting that logic into the new platform.