Senior UI Developer - 12-month contract - BrusselsOne of our important clients is currently looking for a Senior UI Developer for a 12-month contract based in Brussels.Please find the details below:Senior UI Developer – Component Library LeadLocation: Hybrid (2 days/week in office, Monday mandatory)We’re seeking a Senior UI Developer to take full ownership of our core Component Library. You’ll bridge design and technical execution, maintain a high-performance Vanilla JS + SCSS library, and ensure pixel-perfect, accessible, and cross-browser experiences.What You’ll Do:Architect and maintain our component library; ensure modular, reusable, and lean code.Translate Figma designs into high-fidelity, accessible components (WCAG 2.1+, ARIA).Manage NPM package deployment and versioning across dev/prod environments.Test rigorously across browsers & devices (BrowserStack experience preferred).Support integration of Vanilla JS components in React, Next.js, or TypeScript projects.Provide L2/L3 operational support to maintain 24/7 production stability.Maintain comprehensive documentation using Nunjucks; mentor a small developer team.What We’re Looking For:7+ years web/front-end development experience; 5+ years building/maintaining component libraries.Expert in Vanilla JS (ES6+) and SCSS; experience with server-side rendering & APIs.Hands-on experience with headless CMS (Sitecore preferred).NPM package management experience (publishing, SemVer, multi-env).Deep knowledge of accessibility standards and responsive design quirks (especially Safari iOS).Proficiency in Figma and Nunjucks templating.C1+ English, collaborative mindset, strong communicator.Why Join Us:Take ownership of a critical system used across multiple web platforms.Lead a small, talented team and shape best practices.Hybrid flexibility with 2 days/week in-office.If you are interested please send me your CV and I will contact you as soon as possible with further details.