**Responsibilities:** * + Development and maintenance of internal NPM (Node Package Manager) packages, ensuring scalability and consistency; + Configure and optimize *build* processes (Webpack, Vite), focusing on improving performance and developer experience (DX); + Ensure code robustness through the creation of unit tests (Jest, VITest, React Testing Library) and *end\-to\-end* tests (Playwright); + Work closely with Design (UI/UX), Product, and Services teams; + Actively participate in *code reviews* to ensure best practices and team code quality. **Requirements:** * Bachelor's or Master's degree in Computer Engineering or related fields (or equivalent experience); * Minimum of 5 years of experience in React.js development; * Solid knowledge and practical experience with state management libraries such as Redux, Zustand, or Recoil; * Proven experience in creating and publishing NPM packages; * In-depth knowledge of tools such as Webpack and/or Vite; * Strong experience in unit testing (Jest, VITest, React Testing Library) and E2E testing (preferably Playwright); * Proficiency in JavaScript (ES6\+), TypeScript, HTML5, and CSS3; * Experience with API specification, particularly OpenAPI/Swagger, and protocols such as gRPC (advantageous); * Strong problem-solving skills and ability to work independently; * Fluency in English is valued. **Benefits:** * Competitive salary and benefits package; * Continuous training and specific certifications; * Opportunities for professional growth and development; * Dynamic and collaborative work environment; * Growing company with a promising future. * *See how we handle your data at* *www.guestworld.pt*