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For Companies At a Glance
- Tasks: Lead the development of a greenfield SaaS product using C# and AWS.
- Company: Join a fast-paced tech start-up with a focus on innovation.
- Benefits: Earn £700 - £900 per day, fully remote work, and flexible contract.
- Other info: Enjoy a dynamic environment with opportunities for professional growth.
- Why this job: Make a real impact by architecting cutting-edge AI-native solutions.
- Qualifications: Deep expertise in C#, .NET Core, and AWS serverless architecture required.
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 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.
£700 - £900 per day. OUTSIDE IR35. 100% remote. 6 months rolling.
Senior Staff Software Engineer - C#, Agentic Workflows & Native AI Engineering, .Net 8/9, AWS (Lambda, SQS) – OUTSIDE IR35 in Sheffield employer: Smart Sourcer
Contact Detail:
Smart Sourcer Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Senior Staff Software Engineer - C#, Agentic Workflows & Native AI Engineering, .Net 8/9, AWS (Lambda, SQS) – OUTSIDE IR35 in Sheffield
✨Tip Number 1
Network like a pro! Reach out to your connections in the tech industry, especially those who work with C# and AWS. A personal recommendation can make all the difference when you're aiming for that Senior Staff Software Engineer role.
✨Tip Number 2
Show off your skills! Create a portfolio or GitHub repository showcasing your projects, especially those involving .NET Core and serverless architecture. This gives potential employers a taste of what you can do and how you tackle complex problems.
✨Tip Number 3
Prepare for interviews by brushing up on your knowledge of event-driven systems and API design. Be ready to discuss your experience with AWS services like Lambda and SQS, as well as your approach to building resilient applications.
✨Tip Number 4
Don’t forget to apply through our website! We’re always on the lookout for top talent, and applying directly can help us see your application faster. Plus, it shows you’re serious about joining our team!
We think you need these skills to ace Senior Staff Software Engineer - C#, Agentic Workflows & Native AI Engineering, .Net 8/9, AWS (Lambda, SQS) – OUTSIDE IR35 in Sheffield
Some tips for your application 🫡
Show Off Your Skills: Make sure to highlight your deep expertise in C# and .NET Core 8/9. We want to see how you've architected and led the design of distributed REST API microservices, so don’t hold back on those details!
Talk About Your AWS Experience: We’re keen on your authority in AWS serverless architecture. Share specific examples of how you’ve used Lambda, SQS, and other AWS services to ship production workloads. This is your chance to shine!
Demonstrate Your Product Mindset: Since we value a product-centric approach, let us know how you’ve partnered with BAs and made trade-offs in previous projects. Show us that you can own solutions from start to finish!
Keep It Clear and Concise: When writing your application, clarity is key! Use straightforward language and structure your thoughts well. We appreciate a good read, so make it easy for us to see why you’re the right fit!
How to prepare for a job interview at Smart Sourcer
✨Know Your Tech Inside Out
Make sure you’re up to speed with C# and .NET Core 8/9. Brush up on your AWS serverless architecture knowledge, especially Lambda, SQS, and API Gateway. Be ready to discuss your hands-on experience with these technologies and how you've applied them in real-world scenarios.
✨Showcase Your Problem-Solving Skills
Prepare to talk about complex problems you've tackled in previous roles. Think of specific examples where you’ve architected distributed systems or designed event-driven architectures. Highlight your ability to make trade-offs and your product-centric mindset.
✨Communicate Clearly and Effectively
Since this role involves client interaction, practice articulating your thoughts clearly. Be prepared to ask insightful questions that demonstrate your understanding of the project requirements. Good communication can set you apart from other candidates.
✨Demonstrate a Pragmatic Approach
Be ready to discuss how you handle ambiguity and make decisions under pressure. Share examples of how you prioritise tasks and manage technical debt while ensuring high-quality delivery. This will show that you have the outcome-oriented mindset they’re looking for.