C#/.NET Engineer

We are supporting a digital asset infrastructure company whose platform uses cryptographic security and multi-party computation (MPC) to protect and sign digital-asset transactions.

The company is looking for a Senior Backend C#/.NET Engineer to replace a business-critical Excel/VBA spares booking tool with a maintainable application. The engineer must be capable of shaping partially documented requirements, building the application and integrating it with existing stock and ERP processes.

Practical experience using AI coding tools or agents is required, alongside strong independent engineering judgement, testing and verification.

About the Project

Four Excel/VBA workbooks currently support three operational workflows:

1. Spares booking.

2. Substrate stock counting.

3. Label generation.

Spares booking is the first delivery priority. The current workflow records stock withdrawals in Excel for subsequent ERP updates.

The replacement application will:

- Retrieve stock information through an agreed Microsoft Dynamics NAV integration.

- Record booking transactions promptly in a designated SQL table when an operator books stock out.

- Use the client’s existing posting mechanism for subsequent ERP processing.

- Integrate enterprise single sign-on.

- Support existing 2D barcode scanners, subject to confirming device compatibility and input behaviour.

A desktop application is preferred. The .NET version, desktop framework, stock-read interface and detailed integration contract remain to be agreed.

The initial rollout will cover two UK sites. There is interest in wider international use, but the scope and timing of this remain unconfirmed.

Stock counting and label generation will be assessed next to determine whether each should be repaired, retained or replaced. Completion of all workflows within the initial four-month engagement is not guaranteed.

Must-Have Experience and Skills

Technical:

- Strong commercial C#/.NET development experience.

- Experience delivering maintainable desktop applications in C#/.NET.

- Strong SQL capability, including reliable transaction writes.

- Integration with ERP or comparable transactional business systems.

- Ability to read and understand Excel formulas and VBA.

- Enterprise single sign-on integration.

- Practical experience configuring and directing AI coding tools or agents.

- Independent review, debugging and testing of generated code.

- Understanding of data validation, concurrent operations, failed transactions and duplicate submissions.

- Ability to make pragmatic architectural decisions where requirements are

incomplete.

Business and Delivery

- Clear technical English.

- Effective remote working and stakeholder collaboration.

- Ability to work directly with operational users to validate business processes.

- Comfortable owning delivery with limited day-to-day direction.

- Clear communication of dependencies, risks, trade-offs and progress.

Desirable Experience

- Microsoft Dynamics NAV.

- Barcode scanner integration, particularly 2D scanners.

- Stock, inventory, warehouse or manufacturing applications.

- Replacing Excel/VBA tools with supported business applications.

- Delivering software through QA, user acceptance testing and operational

handover.

- No mandatory sector/market experience is required.

Responsibilities

- Analyse the existing workbooks, formulas, VBA and supporting processes.

- Validate intended behaviour with the applications team and operational users.

- Identify defects and obsolete workarounds that should not be carried into the

replacement.

- Agree a prioritised backlog and realistic delivery increments.

- Design and build the C# application using an approved AI-assisted development

workflow.

- Own generated-code review, engineering decisions and testing.

- Implement stock retrieval and booking transaction writes through the agreed

integration.

- Integrate single sign-on and confirm barcode scanner compatibility.

- Agree permissions, transaction history and safeguards during design.

- Support client QA and business user acceptance testing.

- Provide the tested application, deployment instructions and maintenance

documentation.

- Assess the remaining workflows and recommend proportionate next steps.

- Escalate dependencies and scope constraints early.

Team and Client Support

The engineer will work closely with a dedicated member of the client’s applications team, who will:

- Act as the primary link between the developer and business users.

- Own requirements and prioritisation with the business.

- Support SQL integration.

- Perform QA testing.

Business users will undertake UAT. Completion will be signed off by the client’s nominated IT stakeholders. The client owns hosting, identity/access, backups, production deployment and ongoing support. The engineer is responsible for preparing the application and supporting testing and handover

Assessment Process

1. CV Review

2. Screening Call (30 mins) - Technical screening to understand experience

3. Technical assessment/challenge. (1 hr)

4. Final Interview (30 mins) - Cultural fit, collaboration instincts, MVP mindset