Our client is seeking a Senior UI Engineer to take full ownership of a core design system and component library used across multiple digital platforms. The role sits at the intersection of design, frontend engineering, and operational stability, with a strong focus on high-quality, framework-agnostic UI components.
This position combines deep technical craftsmanship with responsibility for accessibility, cross-browser reliability, and production support in a high-availability environment.
Responsibilities:
* Own and evolve a core component library built with Vanilla JavaScript (ES6+) and SCSS, distributed via NPM.
* Translate Figma designs into pixel-perfect, reusable UI components with high visual fidelity.
* Act as the subject-matter expert for accessibility, ensuring strict compliance with WCAG and ARIA standards.
* Manage package versioning and release strategies, maintaining stable production and development streams.
* Ensure consistent behavior across browsers and devices through extensive testing using tools such as BrowserStack.
* Support integration of the component library into various frontend stacks (e.g. TypeScript-, React-, or applications).
* Provide L2/L3 production support and act as an escalation point to ensure UI stability in critical situations.
* Develop and maintain technical documentation and templates using Nunjucks.
* Define and enforce code quality standards, including linting, testing, and architectural guidelines.
What are we looking for?
* You have a minimum of
7 years of professional experience
in
web or frontend development.
* You bring at least
5 years of hands-on experience
building and maintaining component libraries or design systems using
Vanilla JavaScript
and
SCSS
.
* You have proven experience managing
NPM packages
, including publishing and semantic versioning.
* You are proficient with
Figma
and can accurately translate design specifications into technical components.
* You have experience integrating
headless CMS
solutions (Sitecore or equivalent).
* You have hands-on experience with
server-side rendering
and server-side API integration.
* You have worked with cross-browser testing platforms such as
BrowserStack
.
* You are fluent in
English
at
C1 level
or equivalent.
Nice to Haves
* Expert knowledge of mobile browser behavior, particularly
Safari on iOS
.
* Strong understanding of different browser rendering engines (WebKit, Blink, Gecko).
* Experience working in Agile environments with a collaborative, mentoring mindset.
What do we offer?
* Start date: 23/03/2026
* Duration: until 29/02/2028
* Work regime: Full-time
* Location: Brussels
* Working model: Hybrid (2 days onsite per week, Monday mandatory)
* Contract: open to both permanent employees and freelancers