Principal .NET Engineer

Ocho; Belfast; Hybrid; GBP 70,000 - 90,000; Full time

Job summary

A technology-first financial services firm is seeking a Principal .NET Engineer to lead technical decisions and mentor engineers. This hands-on leadership role involves building scalable systems in AWS using .NET Core and Python. The ideal candidate will have deep technical expertise in back-end system design and a passion for engineering excellence.

Qualifications

• Proven experience in a Principal or Lead .NET Engineer role.
• Deep technical expertise in .NET Core and back-end system design.
• Strong working knowledge of AWS and building infrastructure using CDK.

Responsibilities

• Set the technical direction and engineering standards across a growing delivery team.
• Mentor senior and mid-level engineers, reviewing code and guiding architectural decisions.
• Design and deliver back-end systems in .NET Core with an emphasis on resilience.

Skills

Architectural influence

.NET Core expertise

AWS knowledge

Leadership and mentorship

Testing mindset

Tools

AWS CDK

Docker

Kubernetes

Job description

Overview

Principal .NET Engineer – Cloud Infrastructure & Platform Leadership (Hybrid – Belfast or Remote UK)

Are you a technical leader who still loves to code? Do you want to drive architecture decisions, mentor engineers, and shape the future of a cloud-native financial platform?

My client is a technology-first financial services firm undergoing a major platform transformation. They’re now looking for a Principal .NET Engineer to lead the technical direction of a high-impact team building scalable, secure, and performant systems in AWS using .NET Core and Python for Infrastructure as Code.

This is a hands-on leadership role — ideal for someone who wants to balance architecture, mentorship, and high-quality delivery.

What you’ll be doing

• Setting the technical direction and engineering standards across a growing delivery team.
• Mentoring senior and mid-level engineers, reviewing code, and guiding architectural decisions.
• Designing and delivering back-end systems in .NET Core, with a focus on resilience, scalability, and testability.
• Leading Infrastructure as Code adoption using AWS CDK (Python), shaping best practices across environments.
• Driving automation, CI/CD maturity, and a test-first approach across the pipeline.
• Acting as a technical stakeholder – collaborating with Product, Delivery, DevOps, and Architecture.
• Taking ownership of performance, observability, and system health in production.
• Enforcing cloud security best practices and ensuring compliance is built-in, not bolted on.
• Championing agile principles and helping teams continuously improve how they work.

Must-haves

• Proven experience in a Principal or Lead .NET Engineer role – with architectural influence across teams.
• Deep technical expertise in .NET Core and back-end system design.
• Strong working knowledge of AWS – especially building infrastructure using CDK (Python preferred).
• Comfortable leading design discussions, challenging assumptions, and proposing better solutions.
• Strong testing mindset – with experience embedding unit/integration testing into delivery pipelines.
• Experience shaping CI/CD pipelines and deployment workflows.
• Ability to work across disciplines – from infrastructure to architecture to business stakeholders.
• Passionate about mentoring others and driving engineering excellence.

Nice to haves

• Exposure to microservices and event-driven architecture.
• Knowledge of Entity Framework, or similar data access frameworks.
• Experience with Docker; familiarity with Kubernetes (even if DevOps manages orchestration).
• Solid grounding in modern software security and cloud-native compliance.
• Understanding of contract-first development and API standards (e.g. OpenAPI, Swagger).
• Python scripting experience for automation or test tooling.

If you’re ready to play a key role in shaping the technical foundation of a high-growth platform — while staying close to the code — this Principal role offers real influence in a well-funded, modern engineering environment.

If you have any further questions on the role, please feel free to reach out to Brendan McCrory directly.