Senior C# Engineer - Agentic & Native AI Engineering, .NET 8/9, AWS (Lambda, SQS) - OUTSIDE IR35
Posted 1 day ago by Smart-Sourcer
£900 Per day
Outside
Remote
United Kingdom
Summary: This role is for a Senior C# Engineer specializing in Agentic Workflows and Native AI Engineering, focusing on the development of a greenfield SaaS product. The position requires a highly experienced engineer with a strong product-centric mindset and expertise in AWS serverless architecture. The engineer will lead the design and implementation of complex distributed services using C# and .NET Core, while also ensuring high-quality engineering standards. This is a fully remote contract position, classified as outside IR35.
Key Responsibilities:
- Architect, build and ship complex distributed services in C# and .NET Core 8/9, primarily serverless on AWS Lambda.
- Build resilient, event-driven systems using SQS and related AWS messaging primitives.
- Leverage Claude Code, advanced agentic workflows, and native AI engineering practices.
- Own each feature's solution end-to-end, partnering with BAs on high-level problems.
- Design clean, well-versioned, well-documented APIs that prioritize developer experience.
- Champion a high-quality engineering culture with test coverage, peer review, and CI/CD discipline.
Key Skills:
- Deep expertise in C# and .NET Core 8/9, with experience in architecting distributed REST API microservices.
- Authority in AWS serverless architecture, including Lambda, API Gateway, SQS, and IAM.
- Hands-on experience with Claude Code and advanced agentic workflows.
- Expertise in Aurora RDS MySQL and DynamoDB, including schema design and query tuning.
- Proven experience designing event-driven systems with SQS and AWS messaging.
- Strong API design sensibility with a focus on developer experience.
- Excellent communication skills and comfort with client interaction.
- Rigorous engineering standards, including Git-based workflows and CI/CD.
- A pragmatic, outcome-oriented mindset with the ability to handle ambiguity.
Salary (Rate): £900 per day
City: undetermined
Country: United Kingdom
Working Arrangements: remote
IR35 Status: outside IR35
Seniority Level: Senior
Industry: IT
Senior C# Engineer - Agentic Workflows & Native AI Engineering, .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 Workflow.
Skills We're Looking For:
- Senior-Staff-level Back End 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
£875 - £900 per day. OUTSIDE IR35. 100% remote. 6 months rolling.