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

Information Technology

Industries

Pharmaceutical Manufacturing

Barcelona, Catalonia, Spain

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📌 Freelance Senior OR Junior Full Stack Developer – React / Next.js / Node.js – Barcelona
🏢 Blu Selection Recruitment Agency
📍 Barcelona