Principal Software Engineer (UI)
Belfast | Hybrid | Full-Time
At a Glance
- Location: Belfast (Hybrid)
- Employment Type: Full-Time, Permanent
- Seniority: Principal / Senior IC
- Core Stack: React, TypeScript, JavaScript, AWS
- Key Requirement: Strong React and AWS CDK experience essential
Who You'll Work For
Our client is a large, globally operating financial services business with a significant and growing technology function. Their Belfast team is part of a wider engineering organisation, building and maintaining platforms that serve institutional clients at scale.
If you are looking for complexity, breadth, and the opportunity to work on systems that genuinely matter, this is a strong environment for a principal-level engineer.
What You'll Be Doing
As Principal UI Engineer, you will serve as a senior technical authority for UI engineering across multiple teams. This is a hands-on leadership role: you will be writing and reviewing code, setting direction, and raising the bar for how UI systems are designed and delivered.
- Lead the design and development of scalable, high-performance UI applications
- Provide technical leadership and mentoring to UI engineers across teams
- Establish and maintain UI engineering standards, patterns, and best practices
- Oversee solution design, analysis, and implementation for complex UI systems
- Communicate architectural decisions clearly to both technical and non-technical stakeholders
- Guide teams through estimation, planning, and prioritisation using established SDLC processes
- Drive continuous improvement to optimise UI performance, usability, and maintainability
- Identify opportunities to evolve systems toward target architecture and lead refactoring initiatives
- Implement and maintain Infrastructure as Code (IaC) using AWS CDK with Python
- Oversee CI/CD pipeline implementation and management
- Collaborate with Business Analysts and Project Managers to gather and refine requirements
Your Impact
In this role, you will be the person teams look to when the hard architectural questions arise. Your decisions will shape the UI engineering culture, and your hands-on contributions will directly influence the quality and performance of platforms used by professionals in financial markets worldwide. You will mentor engineers, raise standards, and help the organisation move confidently toward its target architecture.
What We're Looking For
Essential
- Proven experience as a senior or principal UI engineer within complex, high-performance systems
- Strong expertise in React, TypeScript, and JavaScript, with deep knowledge of modern UI development practices
- Experience with UI component libraries such as Material UI or Ant Design
- Proficiency in HTML5, CSS, and responsive design principles
- Strong knowledge of performance optimisation and profiling techniques
- Hands-on experience with AWS services and Infrastructure as Code, specifically AWS CDK with Python
- Familiarity with testing frameworks such as Jest and industry code-quality tooling
- Strong command of Git-based source control and agile development methodologies
- Excellent communication and collaboration skills, with the ability to influence engineering direction
Desirable
- Experience with Entity Framework or other ORM/CRM tooling
- Experience designing systems using a contract-first methodology
- Experience writing tests or scripts in Python
- Understanding of microservices architecture in cloud environments
- Experience with relational and/or NoSQL databases
- Proficiency with Docker for containerisation
- Familiarity with Kubernetes
- Experience with CI/CD pipelines and associated tooling
What's In It For You
- A senior individual contributor role with genuine technical authority and influence
- The opportunity to shape UI engineering standards and practices across multiple teams
- A hybrid working model based in Belfast
- A collaborative, inclusive culture within a globally recognised organisation
- The chance to work on platforms that directly support global financial markets infrastructure
If you're interested or have any further questions on the role, please feel free to reach out to Eve Geddis directly on LinkedIn.
