Senior Software Engineer

Leap29; Oxford; On-site; GBP 75,000 - 110,000; Full time

Job summary

Leap29 in Abingdon, Oxfordshire, is seeking a Senior Software Engineer for a 3 days/week onsite role developing complex desktop software used across the global energy industry.

You will take ownership of architecture and engineering decisions, mentor peers, and work closely with leads, scientists and product owners to deliver robust solutions.

Qualifications

• 7+ years of commercial software engineering experience.
• Strong experience with C# and .NET.
• Proven background in desktop applications, ideally WPF.
• Solid CS fundamentals: OOP, algorithms, data structures.
• Knowledge of architecture, design patterns and SOLID.
• Ability to justify technical decisions to stakeholders.
• Experience with automated testing, Git, and CI/CD.
• Track record of taking technical ownership and leadership.
• Experience with large or complex datasets and numerical methods.

Responsibilities

• Design and develop high-quality desktop software using C# and .NET.
• Take ownership of technical solutions from requirements to deployment.
• Assess feature impact on architecture, performance and future work.
• Contribute to product architecture and technical direction with leads.
• Explain technology choices to both technical and non-technical stakeholders.
• Modernise legacy code and promote modern development practices.

Skills

C#

.NET

WPF

Multithreading

CI/CD

Git

Tools

Git

CI/CD

Azure

AWS

Job description

Abingdon, Oxfordshire - 3 days a week onsite

We are looking for a Senior Software Engineer to join a highly skilled team developing complex software used across the global energy industry.

This is an opportunity for an experienced engineer who wants to move beyond simply writing code and take greater ownership of technical decisions, architecture and the evolution of a sophisticated desktop software product.

You will work closely with Technical Leads, Product Owners, Scientists and other engineers to understand complex requirements, assess their impact across the wider product and turn them into robust, maintainable technical solutions.

This is a genuinely hands‑on role. You will remain close to the technology while taking increasing ownership of architecture, technical design and engineering decisions.

What you'll be doing

• Design and develop high-quality desktop software using C# and .NET.
• Take ownership of technical solutions from initial requirements and design through to implementation and deployment.
• Assess new features from a wider product perspective, understanding how technical decisions will impact existing functionality, architecture, performance and future development.
• Contribute to the architecture and technical direction of the product alongside the Technical Lead.
• Make practical technology and design decisions, explaining the reasoning behind your approach to both technical and non‑technical stakeholders.
• Modernise and improve existing desktop and scientific software while helping introduce modern development practices and technologies.
• Apply strong software engineering principles including object-oriented design, SOLID, design patterns, testing and maintainable architecture.
• Work through complex technical problems and translate theoretical software engineering concepts into practical solutions.
• Participate in technical discussions, design reviews and code reviews.
• Work closely with Product Owners, Scientists and stakeholders to understand requirements, challenge assumptions where appropriate and agree the best technical approach.
• Mentor and support other engineers, helping raise technical standards across the team.
• Contribute hands‑on to development where required and remain close enough to the codebase to understand and influence implementation decisions.
• Support continuous improvement across the engineering team, processes and product.

What we're looking for

• 7+ years of commercial software engineering experience, ideally with around 7‑10 years of hands‑on development experience.
• Strong commercial experience with C# and .NET.
• Proven experience developing complex desktop applications, ideally using WPF or similar technologies.
• Strong understanding of Computer Science fundamentals, including object-oriented programming, algorithms and data structures.
• Strong understanding of software architecture, design patterns and SOLID principles.
• Demonstrable experience making technical and architectural decisions rather than simply implementing predefined solutions.
• Ability to explain not only what technology or approach you have used, but why you chose it and how you applied it in practice.
• Experience assessing the wider technical impact of a feature or change across an existing product.
• Experience working directly with Product Owners, Technical Leads, managers and other stakeholders.
• Experience with automated testing, Git, code reviews and CI/CD.
• A track record of taking technical ownership and demonstrating the mindset of a technical lead.
• Strong communication skills with the ability to explain complex technical concepts clearly.
• C or C++ development experience.
• Scientific, engineering, geoscience, geophysics or other technically complex software.
• Experience working with large or complex datasets.
• Numerical algorithms, modelling or simulation.
• Multithreading and concurrent application development.
• Azure, AWS or other cloud technologies.
• Experience modernising legacy applications.
• Experience with AI‑assisted development tools such as GitHub Copilot.
• Experience working within products where performance, reliability and technical accuracy are particularly important.

The type of engineer we're looking for

This role is not simply about having the longest list of technologies on your CV.

We're looking for someone who can explain:

"Here was the problem, these were the options, this is what I decided, this is why I chose it, and this is how I implemented it."

You will be someone who naturally thinks about the bigger picture, challenges technical decisions constructively and understands how an individual feature fits into the wider product.

You may already be acting as a Technical Lead, or you may be a Senior Engineer ready to take that next step.

Most importantly, you'll still want to be hands‑on with technology while taking greater ownership of the technical direction of the product.