Staff/Principal Backend Engineer - C#/.NET/AWS/Agentic AI

UK | Fully Remote (UK-based)

Staff/Principal Backend Engineer (Contract)

6 months | £900/day (Outside IR35)

High-growth Product Engineering Team

Please read the requirements carefully before applying.

Build and evolve a core CRM product used across the business.

We're supporting a product-led organisation that is rebuilding and modernising key areas of an existing CRM platform.

This role suits an experienced contractor who enjoys working in brownfield environments, partnering closely with the business, and shaping how a product evolves rather than just delivering tickets.

You'll operate as a senior, hands-on engineer within a growing engineering group, working closely with senior leadership to take the product from where it is today to where it needs to be next.

The role

This is a product-focused Back End engineering role, not a pure delivery position.

You'll be responsible for rebuilding and enhancing existing CRM capabilities within a live production system, owning Back End services end-to-end and making pragmatic technical decisions in close collaboration with the business. You'll work closely with senior engineers and stakeholders to understand product direction, translate business problems into scalable Back End solutions, and ship iteratively while improving reliability, performance and maintainability.

You'll also contribute to the wider technical direction of the platform as the team scales, helping modernise architecture and set patterns that other engineers build on. This is a collaborative environment with strong access to decision-makers and clear product ownership.

Core technical experience required

• C#
• .NET (Back End services and APIs)
• Strong agentic AI development, including hands-on experience with LLMs, multi-agent orchestration and RAG-style systems
• AWS, with a serverless and cloud-native mindset

Please note these requirements are non-negotiable. Unfortunately, the client is not flexible on Azure, nor on candidates whose AI experience is limited to assisted development only.

What they're looking for

• Senior or Staff-level Back End engineer with a strong product mindset
• Experience modernising and extending existing platforms in live environments
• Comfortable operating beyond code, engaging with the business and explaining trade-offs clearly
• Confident communicator, able to work effectively with non-technical stakeholders
• Pragmatic and outcome-focused, prioritising progress and impact over perfection

Working model & contract details

• 6-month contract (extensions likely)
• £900/day, Outside IR35
• Fully remote within the UK
• Occasional office attendance may be required