Senior Engineer, Platform (C#)

Oak Engage; United Kingdom; Hybrid; GBP 60,000 - 80,000; Full time

Job summary

A leading SaaS company in the UK is seeking a Senior Back-End Engineer to drive the evolution of their server-side systems. The ideal candidate will have over 5 years of experience in C# and .NET, focusing on designing robust back-end services and optimising performance. This role offers hybrid working options and a chance to solve real-world challenges for prominent brands, along with a comprehensive benefits package.

Benefits

Private health insurance

Life insurance

Employee Assistance Programme (EAP)

Gym contribution

Travel allowance

Generous holiday policy (25 days + Bank Holidays + additional discretionary days)

Qualifications

• 5+ years in back-end development with C#/.NET and experience at scale.
• Deep understanding of software design patterns, systems architecture, and secure development.
• Experience working in agile environments with modern DevOps toolchains.

Responsibilities

• Design and develop robust back-end services and APIs using C# and .NET Core/.NET 6+.
• Optimise system performance, security, and scalability for a growing customer base.
• Collaborate with product and other stakeholders to shape Oak's technical strategy.

Skills

C#/.NET

API design with focus on security

Docker

CI/CD

Agile methodologies

Strong communication

Tools

Azure

Job description

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Location: Hybrid, Newcastle or Remote (UK Based)
Reports to: Engineering Manager
Type: Full-time

Join Oak Engage – Where Communication Meets Connection

At Oak Engage, we’re on an exciting growth journey—backed by a major investment from NorthEdge to scale our impact and redefine the future of employee engagement. Trusted by some of the UK’s biggest brands, including Aldi, Five Guys, and ITV, we help organisations connect, engage, and empower their people through smarter, more personalised internal communication. With our next stage of expansion underway, we’re building a team of bold, ambitious thinkers ready to make their mark at a high-growth, purpose-driven SaaS company. If you’re looking to shape the future of work and grow alongside a company that’s going places, now’s the time to join Oak.

About the Role

We’re looking for a Senior Back-End Engineer with deep expertise in C#/.NET to drive the evolution of Oak’s server-side systems. You’ll take ownership of designing and delivering high-availability, high-performance services, working at the core of a product used by some of the UK’s biggest brands.

This is a strategic, hands-on role perfect for someone who enjoys solving complex technical challenges, shaping architecture, and supporting product growth at scale.

What You’ll Do

• Design and develop robust back-end services and APIs using C# and .NET Core/.NET 6+
• Optimise system performance, security, and scalability for a growing customer base
• Guide architectural decisions around microservices, data storage, and integrations
• Collaborate with product and other stakeholders to shape Oak's technical strategy and roadmap.
• Mentor junior engineers and contribute to technical best practices
• Drive automation, observability, and CI/CD maturity

Requirements

What We’re Looking For

• 5+ years in back-end development with C#/.NET and experience at scale
• Deep understanding of software design patterns, systems architecture, and secure development
• "Experience designing APIs with a strong focus on security and best practices."
• "Comfortable working with CI/CD pipelines, Docker, and cloud infrastructure; Azure experience is advantageous."
• Experience working in agile environments with modern DevOps toolchains
• Strong communicator and technical collaborator
  

Why Join Oak?

• A meaningful role in a mission-led SaaS company with strong growth and product-market fit
• The chance to work with household brands and solve real-world enterprise challenges
• Flexible hybrid or remote working options
• Private health insurance, life insurance, and Employee Assistance Programme (EAP)
• Gym contribution and travel allowance
• Enhanced maternity, paternity, and discretionary leave
• Generous holiday policy (25 days + Bank Holidays + additional discretionary days)
• Regular team socials and a positive, collaborative culture

Our Recruitment Process

• Deep dive into architecture, problem-solving, and team contributions
• Assess communication and curiosity

Technical Task or Live Pairing

• Realistic, time-bound task or live coding session
• Use structured rubric for fairness (avoid freeform “whiteboarding”)
• "Focus on team collaboration, code quality, and feedback"

Peer Technical Panel/Culture Fit / CTO Chat - In person at our NCL HQ

• Assess long-term growth potential and alignment with tech principles
• Opportunity for candidate to ask strategic questions

Equality & Diversity at Oak

At Oak, we’re committed to building a diverse and inclusive workplace where everyone feels welcome, supported, and able to thrive.

We believe that different perspectives make us stronger, and we actively encourage applications from people of all backgrounds, experiences, and identities — including, but not limited to, race, ethnicity, gender, age, disability, sexual orientation, and socio-economic status.

We are an equal opportunities employer. All hiring decisions are based on business needs, role requirements, and individual qualifications — without bias or discrimination.

If you require any adjustments to the interview process or the role itself to support accessibility, please let us know — we’re happy to help.