Principal JS Developer

Principal Software Engineer At a Glance Principal-level React engineering role... lead, mentor, and still code React, JavaScript (ES6/7+), D3.js... data-rich merchant-first platforms at scale Fully remote across the UK and Ireland Shape the front-end architecture, design system, and component library from the ground up Small, empowered teams with real autonomy and genuine technical influence About the Company Our client is building the next generation of cloud-based payment and merchant solutions. Their platforms are data-rich, customer-facing, and built for scale, powering portals, hosted payment pages, and reusable component libraries used by merchants across the market. Technology is central to their product and this hire will help shape how it evolves.

The Role This is a Principal-level engineering position for someone who wants to lead without stepping away from the code. You will shape the design and delivery of front-end systems, collaborate with UX and Product to build intuitive merchant-facing applications, and define the standards that other engineers work to. If you are a senior React engineer who has outgrown purely individual contributor work but has no desire to move into management, this is the role.

Key Responsibilities Lead the design and delivery of front-end applications using modern JavaScript and React Translate prototypes into pixel-perfect, responsive, accessible user interfaces Build and maintain a reusable component library and help define the design system Collaborate with UX, Product, and Engineering to deliver merchant-first solutions from requirements through to release Mentor engineers, provide technical direction, and foster front-end best practices across teams Support deployment activities and ensure quality and reliability at scale What You'll Need Essential: 10+ years of software engineering experience with strong front-end expertise Deep knowledge of JavaScript (ES6/7+), React, HTML, and CSS (SASS, LESS, or SCSS) Strong design sense with experience delivering data-rich applications using D3.js or similar Experience integrating with REST APIs and modern authentication (OAuth2 / OIDC) Track record of building scalable, performant front-end systems Comfortable mentoring, coaching, and providing technical leadership across engineering teams Right to work in the UK or Ireland Nice to Have: Experience with Vue or Angular in addition to React Background in fintech or other regulated industries Why Apply? Fully remote across the UK and Ireland Principal-level technical leadership without stepping away from the work you enjoy Small, empowered teams with real autonomy and visible impact Inclusive culture where growth, learning, and collaboration are genuinely prioritised Shape the front-end architecture, design system, and component library from the ground up Next Steps Connect with Ryan Quinn on LinkedIn for an informal chat, or reach out at Skills: JavaScript AWS TypeScript WHJS1_NI