UI Developer – Design Systems & Component Libraries

Our client, a prominent organization in the transportation sector, is seeking a specialized professional to take full ownership of their core component library. This role focuses on bridging the gap between design and technical execution by maintaining a high-performance design system and ensuring operational resilience across web platforms.

• Architect and maintain the core component library using high-quality Vanilla JS and SCSS to ensure modular and reusable code.
• Translate design specifications and prototypes from Figma into pixel-perfect technical components.
• Lead accessibility initiatives by building components that strictly adhere to WCAG 2.1+ and ARIA standards.
• Manage the deployment lifecycle and package versioning of the library via NPM across development and production environments.
• Execute rigorous multi-device and cross-browser testing using platforms like BrowserStack to ensure seamless performance.
• Collaborate with cross-functional development teams to integrate components into TypeScript, React, or Next.js projects.
• Provide L2/L3 production support and troubleshooting to guarantee 24/7 system stability and uptime.

• You have 7+ years of professional experience in front-end web development.
• You bring 5+ years of hands-on experience building and maintaining design systems or component libraries with Vanilla JavaScript (ES6+) and SCSS.
• You're experienced in managing NPM packages, including publishing, SemVer strategies, and multi-environment maintenance.
• You possess hands-on experience with cloud-based testing tools such as BrowserStack to debug across various browser engines.
• You have expert-level knowledge of web accessibility standards, specifically WCAG 2.1+ and ARIA roles.
• You bring proficiency in Figma with the ability to inspect designs and extract assets for high-fidelity technical implementation.
• You have experience with server-side rendering (SSR) and server-side API integration.
• You possess experience integrating a headless CMS, with a preference for Sitecore.
• You're proactive, solution-oriented, and capable of managing competing priorities in a high-pressure environment.
• You are fluent in English with C1 level proficiency.

Nice to Haves

• Solid grounding in Agile methodologies and iterative growth.
• Deep understanding of Nunjucks for templating and documentation generation.
• Familiarity with how different rendering engines like Webkit, Blink, and Gecko handle CSS and JS.
• Knowledge of mobile responsiveness strategies specifically for Safari on iOS.

• Start date: 07/05/2026
• Duration: until 29/02/2028
• Work regime: Full-time
• Location: Brussels
• Working model: Hybrid (2 days onsite per week, with Monday being mandatory)
• Contract: open to both permanent employees and freelancers