Freelance Développeur Front-End / React - Spécialiste Design System H/F

Senior Design System Engineer

Type of position: Temporary
Compensation: 550 € Daily
Start date: June 2026
Aquent is looking for a freelance Senior Design System Engineer fluent in English for one of its clients, an international group that pushes the boundaries of user experience.
The goal of this mission is highly strategic: to lead the maintenance, evolution, and scaling of their Design System.
Your Key Responsibilities
Within an international team, your missions will be:
Advanced UI Engineering & Multiversion: Design, optimize, and evolve the components of the React and advanced TypeScript library. Manage the compatibility and migration to React 18 and React 19, as well as communication around breaking changes.
Performance & Complex Ecosystem: Solve complex issues related to server-side rendering (SSR) and the architecture of the Next.js ecosystem used by dozens of consuming teams.
Design-to-Code Alignment: Ensure perfect synchronization and parity between production code and the Figma environment (tokens, variables, library architecture).
Innovation & AI Integration: Collaborate on the implementation of generative AI tools within the Design System (e.g., creating onboardings to allow non-technical profiles to generate code via the system).
Support & Evangelism: Accompany and guide the community of internal developers who consume the library on an international scale.
Other Requirements

Profile Sought
Indispensable Technical Skills:

Absolute React Expertise: In-depth knowledge of React’s internal mechanics, multi-versioning management (18 and 19), and SSR/Next.js issues.
Large-Scale Design System Specialization: You have already deployed, maintained, and documented a library/components consumed by multiple users and teams. Having created a simple Storybook library for a small project is not sufficient for this position.
AI & Automation (Mandatory): Strong curiosity and willingness to use AI on a daily basis. The group actively uses AI to automate its workflows, and an open-minded attitude towards these tools is a disqualifying criterion.
Secondary Hard Skills: Advanced TypeScript, Storybook, testing tools.
Fluent / Operational English Mandatory: International team, daily meetings are conducted entirely in English.
Resilience & Autonomy: Ability to evolve calmly and structured in a shared governance team context.
Service Sense: Team spirit, clarity in the documentation of migrations and releases.