Smart Sourcer

Senior C# Engineer – Agentic & AI Engineering (Claude Code), .Net 8/9, AWS (Lambda, SQS) – OUTSIDE IR35

 

Reporting to the Director of Engineering, this is a genuinely outstanding contract opportunity for a rockstar Senior C# Engineer to lead the development of a greenfield SaaS product. We’re looking for a ‘best of breed’, deeply senior, technically hands‑on engineer who thrives in complex problem spaces and fast-moving start-up & scale-up environments. You’ll need a genuinely Product Centric mindset and approach twinned with experience of AI‑Native Engineering and Agentic Workflows.

 

Skills We’re Looking For:

 

* Senior–Staff‑level backend engineer with deep, current expertise in C# and .NET Core 8/9, capable of architecting and leading the design of distributed REST API microservices at scale.
* Authority in AWS serverless architecture; Lambda‑first, with strong working knowledge of API Gateway, SQS, Step Functions, EventBridge and IAM, and a track record of shipping production workloads on this stack.
* Hands‑on experience with Claude Code (or similar) and advanced agentic workflows; multi‑agent orchestration, context management, custom commands/skills and scaling AI‑assisted delivery across a team.
* Expertise across Aurora RDS MySQL and DynamoDB; schema design, access patterns, indexing, query tuning, single‑table vs multi‑table trade‑offs, and pragmatic thinking around consistency, scaling and cost.
* Proven experience designing event‑driven systems with SQS and adjacent AWS messaging; idempotency, retries, ordering, DLQs and operational robustness.
* Strong API design sensibility; versioning, documentation, throttling, backwards compatibility and a genuine obsession with developer experience.
* A strong product brain; comfortable operating without a traditional Product Owner, partnering with BAs, making sensible trade‑offs, prioritising ruthlessly and owning the solution through to delivery.
* Excellent communication skills and comfort with ad‑hoc client interaction, able to ask the right questions, shape requirements and translate outcomes into shippable work.
* Rigorous engineering standards; Git‑based workflows, trunk‑based development, CI/CD (ideally GitHub Actions), IaC (AWS CDK or Terraform), comprehensive testing and secure‑by‑default coding.
* A pragmatic, outcome‑oriented mindset; comfortable with ambiguity, biased to shipping, and able to make sensible calls on scope, sequencing and technical debt.

 

What You’ll Own & Deliver:

 

* Architect, build and ship complex distributed services in C# and .NET Core 8/9, primarily serverless on AWS Lambda, setting the technical bar for the squad and delivering major feature sets end‑to‑end.
* Build resilient, event‑driven systems using SQS and related AWS messaging primitives; idempotency, retries, DLQs, ordering and clean service boundaries.
* Leverage Claude Code, advanced agentic workflows and native AI engineering practices; orchestrating sub‑agents, managing context, running parallel workstreams and embedding AI‑native engineering patterns into everyday delivery.
* Own each feature’s solution end‑to‑end; partnering with BAs on high‑level problems, then driving product thinking, scoping, trade‑offs and delivery yourself.
* Design clean, well‑versioned, well‑documented APIs that other engineers love to consume; treating developer experience and contract stability as first‑class concerns.
* Champion a high‑quality engineering culture; test coverage, peer review, CI/CD discipline (GitHub Actions), IaC, secure coding, observability and performance

 

£750 - £800 per day. OUTSIDE IR35. 100% remote. 11 months rolling.

Amazon

AWS Lambda

Testing

Continuous Integration

Web Development

Microservices

MySQL

Security software

Serverless

Project documentation

Communications

Terraform

System security

Lambda

Amazon SQS

.NET Core

Amazon RDS

DynamoDB

API Gateway

Aws step functions

Aws iam

CI/CD

GitHub Actions

AWS CDK

Senior C# Engineer - Agentic & AI Engineering (Claude Code), .Net 8/9, AWS (Lambda, SQS) – OUTSIDE IR35