At a Glance
- Tasks: Lead the development of a greenfield SaaS product using C# and AWS technologies.
- Company: Innovative tech firm focused on AI-native engineering and distributed systems.
- Benefits: Competitive daily rate, fully remote work, and a dynamic contract role.
- Other info: Opportunity to influence engineering culture and drive impactful projects.
- Why this job: Shape the future of technology while solving complex problems in a supportive environment.
- Qualifications: Senior-level experience in C#, .NET, and AWS serverless architecture.
The predicted salary is between 60000 - 80000 £ per year.
A rare opportunity to lead the build of a greenfield SaaS product as a deeply senior, hands-on C# engineer. Reporting directly to the Director of Engineering, you'll operate as the technical spearhead; shaping architecture, driving AI-native engineering patterns, and delivering complex distributed systems at pace.
We're looking for someone who is product-centric, agentic-minded, and thrives in ambiguity. If you enjoy solving hard problems, owning outcomes end-to-end, and setting the engineering bar for others, this one's for you.
What You'll Bring:
- Senior/Staff-level backend engineering depth in C# and .NET 8/9, with the ability to architect and lead distributed REST microservices at scale.
- Strong authority in AWS serverless: Lambda-first, with hands-on experience across API Gateway, SQS, Step Functions, EventBridge and IAM.
- Practical experience with Claude Code (or similar) and advanced agentic workflows - multi-agent orchestration, context management, custom commands/skills, and scaling AI-assisted delivery.
- Deep data expertise across Aurora MySQL and DynamoDB - schema design, access patterns, indexing, query tuning, and pragmatic trade-offs around consistency, scale and cost.
- Proven ability to design event-driven systems with SQS: idempotency, retries, ordering, DLQs and operational robustness.
- Strong API design sensibility: versioning, documentation, throttling, backwards compatibility and a genuine obsession with developer experience.
- A product-first mindset - comfortable operating without a traditional PO, partnering with BAs, shaping requirements and owning delivery.
- Excellent communication skills and confidence in ad-hoc client interaction.
- Rigorous engineering standards: Git-based workflows, trunk-based development, CI/CD (GitHub Actions), IaC (CDK/Terraform), comprehensive testing and secure-by-default coding.
- Pragmatic, outcome-oriented, comfortable with ambiguity and biased toward shipping.
What You'll Own:
- Architecting, building and shipping complex, high-performance distributed services in C#/.NET 8/9 on AWS Lambda.
- Designing and delivering resilient event-driven systems using SQS and related AWS messaging primitives.
- Embedding AI-native engineering and agentic workflows into everyday delivery - orchestrating sub-agents, managing context, and running parallel workstreams.
- Owning features end-to-end: product thinking, scoping, trade-offs, sequencing and delivery.
- Designing clean, well-versioned, well-documented APIs that other engineers love to consume.
- Championing a high-quality engineering culture: testing discipline, peer review, CI/CD excellence, observability, performance and secure coding.
Contract Details:
- £750-£800/day
- Outside IR35
- 100% remote (UK)
- 11-month rolling contract
Senior C# Engineer - Agentic Engineering, .NET 9, AWS Lamba & SQS in City of London employer: Smart Sourcer
As a Senior C# Engineer at our innovative company, you will be part of a dynamic and forward-thinking team that values creativity and technical excellence. We offer a fully remote work environment, competitive daily rates, and the opportunity to lead the development of cutting-edge SaaS products while fostering your professional growth through hands-on experience with advanced technologies like AWS and AI-native engineering. Join us to shape the future of technology in a culture that prioritises collaboration, quality, and impactful outcomes.
StudySmarter Expert Advice🤫
We think this is how you could land Senior C# Engineer - Agentic Engineering, .NET 9, AWS Lamba & SQS in City of London
✨Make Your Portfolio Shine
As a freelancer in software development, your portfolio is your bread and butter. Showcase not only your completed projects but also your coding skills on platforms like GitHub or GitLab. This visibility can lead to clients reaching out to you directly!
✨Join Developer Communities
Get involved in developer communities like Stack Overflow or Reddit's r/programming. Contributing to discussions, sharing your knowledge, or even helping others can expand your network and lead to freelance opportunities. Plus, it keeps you in the loop about what’s trending in software development.
✨Freelance Platforms Are Your Friend
Sign up for popular freelance platforms such as Upwork or Freelancer. They’re filled with people looking for talent like yours! Don’t forget to personalise your pitch to each potential client, highlighting how your unique skills can solve their specific problems.
✨Utilise Your Network
Don’t hesitate to reach out to your existing contacts - you never know who might need your services or can refer you to someone who does. Personal connections can lead to more reliable gigs than cold applications. And we're here to help too! If you're looking for freelance opportunities, check out opportunities listed on our website.
We think you need these skills to ace Senior C# Engineer - Agentic Engineering, .NET 9, AWS Lamba & SQS in City of London
Some tips for your application 🫡
Showcase Your GitHub Projects:When applying for a freelance software engineering gig at Smart Sourcer, make sure to include your GitHub link in your application. Highlighting your code repositories, contributions to Open Source, and any personal projects can really set you apart and give us insight into your skills and coding style.
Tailor Your CV with Relevant Skills:In software development, the specifics matter! Make sure your CV lists the programming languages and technologies you excel at. Focus on the ones that align with the projects Smart Sourcer is working on. Listing your tech stack clearly will help us understand how you fit into our team.
Include a Portfolio of Your Work:A solid portfolio is a must when applying for freelance roles. Include links to any apps, websites, or software you've developed. Highlight any projects that reflect a strong user experience, efficiency, or innovative solutions—this is your chance to shine and show us what you can bring to the table!
Mention Your Availability and Rates:Since this is a freelance role, we want to know when you’re available and what your rates are like! Be upfront about your typical work hours and project timelines. This transparency will help us see if we can sync up for future projects at Smart Sourcer.
How to prepare for a job interview at Smart Sourcer
✨Showcase Your Code Wizardry
Since you're going for a freelance role in software engineering, have a solid portfolio ready to flaunt your best work. Include projects that highlight your coding skills, frameworks you excel in, and any problem-solving feats you've pulled off. This is your chance to shine, so choose pieces that reflect your unique style and expertise!
✨Prepare for Technical Challenges
Freelance gigs often involve tech assessments or coding challenges, so be ready to tackle some hands-on problems. Brush up on common algorithms, data structures, and any languages/frameworks relevant to the role at Smart Sourcer. Being comfortable with platforms like HackerRank or LeetCode can give you an edge and showcase your skills under pressure!
✨Be Clear About Your Rates and Flexibility
As a freelancer, be prepared to discuss your rates upfront. It's crucial to communicate your pricing structure clearly and whether you're open to negotiation. Do your homework on industry standards to ensure you pitch a fair and competitive rate that reflects your skills and experience!
✨Understand Their Tech Stack
Before the interview, get familiar with the tools and technologies used at Smart Sourcer. Whether it's a particular framework or a specific coding methodology, being knowledgeable about their tech stack not only shows your interest but also helps you present how you could fit seamlessly into their existing projects. Demonstrating you’ve done your homework can set you apart from other candidates!
