Senior C# / WPF Engineer – Risk System Replatforming

JUXT; Greater London; On-site; GBP 90,000 - 150,000; Full time

Job summary

JUXT is seeking a Senior C# Engineer with strong WPF experience to join our risk system replatforming programme. You will own key desktop components, modernise legacy apps, and ensure performance, reliability and security in a mission-critical financial technology environment.

You will design across the full SDLC, build high‑quality WPF UIs, contribute to CI/CD pipelines, automated testing, and production support.

Qualifications

• Experience delivering enterprise C#/.NET desktop applications.
• Strong WPF UI development for complex dashboards.
• Proven testing strategy including unit/integration/UI tests.

Responsibilities

• Design, develop and maintain high-performance C#/.NET and WPF applications.
• Modernise and refactor legacy desktop applications as part of the replatforming programme.
• Take ownership of individual components and workstreams.

Skills

C# / .NET

WPF

Testing

CI/CD

Financial markets experience

Tools

NUnit

xUnit

Job description

A global Tier 1 investment bank is undertaking a major Risk System Replatforming Programme, modernising a suite of legacy desktop applications and risk technology used within a complex financial environment.

We're looking for a Senior C# / WPF Engineer to join the engineering team and take ownership of key components of the replatforming programme. You'll be responsible for modernising and refactoring existing applications while maintaining performance, reliability and functional integrity throughout the transition.

This is a hands-on engineering role suited to someone who enjoys working with complex systems, solving difficult technical problems and taking ownership of delivery with minimal supervision.

The Role

You'll work across the full software development lifecycle, from understanding existing legacy architecture and designing modern solutions through to implementation, automated testing, deployment and production support.

The role is particularly suited to engineers who have experience with C#, WPF and the .NET ecosystem, combined with strong engineering practices around testing, CI/CD and code quality.

Experience within risk, trading or financial markets would be highly advantageous, particularly where you've worked with complex data flows or applications supporting front-office or risk functions.

Key Responsibilities

• Design, develop and maintain high-performance C#/.NET and WPF applications.
• Modernise and refactor legacy desktop applications as part of the wider replatforming programme.
• Take ownership of individual application components and replatforming workstreams.
• Analyse existing architecture and identify opportunities to improve maintainability, scalability and performance.
• Develop modern WPF user interfaces supporting complex financial and risk workflows.
• Work closely with other engineers, architects and business stakeholders to understand requirements and technical constraints.
• Develop robust automated unit, integration and UI tests to protect against regression during migration.
• Contribute to CI/CD pipelines, automated deployments and software quality controls.
• Investigate and resolve production issues and technical blockers independently.
• Perform root-cause analysis and implement sustainable solutions rather than temporary fixes.
• Participate in code reviews and contribute to engineering standards and best practices.
• Communicate technical progress, risks and dependencies clearly to project stakeholders.
• Ensure solutions are secure, reliable, maintainable and appropriate for a mission-critical banking environment.
• Support the transition from legacy technology towards a modernised application architecture.

Essential Technical Skills

C# / .NET

• Excellent understanding of the .NET ecosystem.
• Strong object-oriented programming and software engineering fundamentals.
• Experience working with complex, enterprise-scale applications.

WPF

• Deep hands-on experience with Windows Presentation Foundation (WPF).
• Experience building complex desktop user interfaces.
• Experience modernising, migrating or refactoring existing WPF applications.
• Strong understanding of desktop application architecture and performance considerations.

Testing

Strong automated testing experience, including:

• NUnit or xUnit
• Unit testing
• Integration testing
• UI testing
• Regression testing
• Automated quality gates

The successful candidate should understand how to build an effective testing strategy around a large-scale application migration and use automation to minimise regression risk.

CI/CD

Experience working with modern software delivery pipelines, including:

• Automated builds
• Automated testing
• Automated deployments
• Code quality and governance controls

Financial Markets / Risk Experience

Experience within financial services is strongly preferred.

Particularly valuable experience includes:

• Market risk
• Trading applications
• Front-office technology
• Trading floor environments
• Financial analytics

A candidate who understands how technology supports risk management and trading workflows will be particularly well positioned to succeed in the role.

We're looking for someone who can operate with a high degree of autonomy.

You should be comfortable:

• Taking ownership of a defined technical workstream.
• Managing competing priorities.
• Working through ambiguity.
• Identifying and resolving blockers without waiting for detailed direction.
• Making pragmatic technical decisions.
• Working effectively with distributed engineering teams.
• Communicating progress and risks proactively.
• Driving work through design, development, testing and production.

Software Engineering Principles

The team places strong emphasis on engineering quality. You'll be expected to demonstrate:

• Clean, maintainable code.
• Automated testing.
• Code review discipline.
• Performance awareness.
• Observability and operational awareness.

The Ideal Candidate

The ideal candidate will be a Senior C# Engineer with significant WPF experience who has worked on complex desktop applications and understands the challenges associated with modernising legacy technology.

You'll ideally combine:

C# + WPF + .NET + Automated Testing + CI/CD + Legacy Modernisation + Financial/Risk Systems

You should also be comfortable working independently, taking ownership of technical problems and communicating effectively with both engineers and senior stakeholders.