UI Design System Designer

You will work on a large, existing ecosystem of internal applications used daily by professionals. Over the years, these applications have grown organically, resulting in visual inconsistencies, UX friction, and increasing UI debt. The goal of this mission is to create the foundations of a Design System that becomes the single source of truth for all interfaces. This Design System will help align user experience, reduce UI debt, speed up product design and development, and ensure accessibility compliance.

The primary focus is internal, desktop-first business applications, with responsive behaviour for mobile consultation.

What you’ll do

• You audit existing applications to understand current UI patterns, inconsistencies, and UX pain points.
• You build a structured UI inventory covering colours, typography, components, layouts, and interaction patterns.
• You define the visual foundations of the Design System, including design tokens for colours, typography, spacing, grids, and UI variables.
• You design and deliver a first UI component library (UI Kit) in Figma, following best practices such as auto-layout, variants, and shared libraries.
• You ensure all components and interactions comply with accessibility standards (WCAG).
• You design with a desktop-first mindset, while ensuring responsive behaviour for mobile usage.
• You document clear usage guidelines for components, including do’s and don’ts, to enable consistent adoption by designers and developers.
• You collaborate closely with internal teams to ensure the Design System is usable, scalable, and aligned with real product needs.
  

What are we looking for?

• You have proven experience designing UI/UX for complex application ecosystems, not just marketing websites.
• You have hands-on experience creating or contributing to Design Systems and reusable UI component libraries.
• You are very comfortable working with Figma, including auto-layout, variants, variables, and shared libraries.
• You understand accessibility principles and have applied WCAG 2.1 (or higher) in real projects.
• You are able to audit existing interfaces and translate findings into structured, actionable design decisions.
• You understand basic front-end constraints and can design components that are realistic to implement.
• You can clearly document your work and explain design decisions to non-designers.
• You are fluent in French.
• Knowledge of English and/or Dutch is a plus.
  

Nice to have

• Experience with enterprise or public-sector applications.
• Experience designing desktop-first business tools.
• Exposure to cartographic or data-heavy interfaces.
• Experience documenting Design Systems using tools such as zeroheight or Storybook.
  

What do we offer?

Location: Brussels (hybrid, minimum 2 days on site)

Start date: January 2026

Duration: Until end of March 2026

Contract: Freelance