At RSI We?re looking for a part time full-stack developer to help us transition from a legacy PHP/JavaScript application to a modern React + Next.js framework. You'll collaborate with our internal team to refactor backend logic, gradually migrate features, and implement new components using modern frontend practices. You?ll work in a sandboxed environment using version control processes, with all changes reviewed and deployed internally. This role includes no direct access to production systems. What you´ll do - Refactor legacy PHP/MySQL code into modular, framework-compatible components - Build and implement new features using React + Next.js - Migrate existing frontend logic and UI to modern frontend architecture - Write clean, testable, and well-documented code using Git workflows (branches, pull requests, etc.) - Collaborate with internal developers to ensure compatibility with staging/test environments - Participate in architectural planning and framework migration strategy Required Education and Experience: - 3?5+ years of full-stack development experience - Strong experience with PHP + MySQL (legacy cleanup and refactoring) - Proven experience with React and Next.js for building modern web applications - Strong JavaScript fundamentals (async, DOM manipulation, REST APIs) - Comfortable with Git-based workflows (branching, PRs, staging) - Ability to write modular, maintainable, and well-documented code - Solid written communication skills in English (B2-C1 level)