Freelance Senior OR Junior Full Stack Developer – React / Next.js / Node.js – Barcelona You will collaborate closely with the Tech Lead, Product Owner, UX Designer, and Data team to design, develop, and deliver high-quality features within an agile environment. Responsibilities * Develop and maintain complex, data-heavy user interfaces using React and Next.js * Build and optimise reusable components and contribute to the internal UI library * Design and integrate REST APIs and WebSocket endpoints * Ensure code quality through clean architecture and best practices * Write unit and integration tests (Jest / Testing Library) * Collaborate with Product, UX, and Data to deliver features end-to-end * Participate in architecture discussions and decision-making * Troubleshoot and resolve issues across the stack * Contribute to CI/CD processes and development workflow improvements * Maintain documentation on Confluence Required Qualifications * 3-5+ years of experience as a Full Stack or Front-End Engineer * Strong hands-on experience with React.js and Next.js * Experience building and consuming REST APIs * Good understanding of backend technologies (Node.js required; Python/FastAPI is a plus) * Experience with component libraries, design systems, or shared UI components * Familiarity with modern testing frameworks (Jest, Testing Library) * Good understanding of performance, security, and scalability principles * Comfortable working in cross-functional agile teams * Strong communication skills in English Nice to Have * Experience with container technologies ( Docker, AWS ECR/EKS, OpenShift) * Experience with CI/CD pipelines * Knowledge of SonarQube, Checkmarx, or similar code quality tools * Experience in healthcare, pharma, or other regulated environments What We Offer * Full-time freelance mission * 3-month contract, renewable depending on performance and roadmap * Hybrid environment from Barcelona Seniority level Mid-Senior level Employment type Full-time Job function Inf

📌 Freelance Senior OR Junior Full Stack Developer (Barcelona)
🏢 Blu Selection Recruitment Agency
📍 Barcelona