Mid/senior React Developer (MUI 9 migration)

React & MUI 9:

• Expert-level React knowledge, including Hooks, Context, performance, and composition patterns.
• MUI v9, including migration from v4/v5, theme customization, and sx system.
• Composite component design, including App Shell, Panel Layouts, and Form Structures.
• Design token integration and tree-shaking, including icons and bundle optimization.

SSR / CSR / Next.js:

• Deep understanding of SSR and CSR, including differences, implications, and tradeoffs.
• Next.js, including SSR-compatible component development without retrofitting.
• Ability to identify and prevent hydration issues.

Library & Tooling:

• Building and maintaining shared component libraries, including monorepo setup.
• Storybook, including documentation, controls, and lifecycle management.
• TypeScript, including type-safe component interfaces.
• Figma handoff and design token propagation.

Architecture (nice to have):

• Micro-frontend architectures.

• White-label theming and multi-tenant systems.

• CI/CD for component libraries, including versioning and publish workflows.

• At least 5 years of relevant frontend experience.

• Proven experience building or maintaining component libraries.

• Experience in cross-team projects with multiple product teams.

• Technical inventory, including CSR vs. SSR and existing implementations per application.
• Build the central MUI 9-based component library.
• Develop composite components: App Shell, Header, Panel Layouts, Form Structures.
• Define design tokens and theme infrastructure, including colors, typography, and branding.
• Implement all components to be SSR-compatible from day one, including Next.js / Service Requests.
• Set up and maintain Storybook documentation, lifecycle-oriented.
• Handle Figma handoff and propagate design decisions into the product.
• Pilot components in real modules of selected applications.

Only candidates located in Poland are eligible for remote work.