Freelance Senior Or Junior Full Stack Developer - React / Next.Js / Node.Js - Barcelona
Freelance full-stack developer (junior or senior) building data-heavy user interfaces with React/Next.js and Node.js backends (REST, WebSockets) for a pharmaceutical company in Barcelona. 3-month renewable contract, hybrid from Barcelona, working with Product, UX and Data in an agile team.
- Compensation
- Not disclosed
- Location
- Barcelona, Spain
- Work setup
- Not specified
- Seniority
- Senior
- Employment
- Contract
- Experience
- 5+ years
- Category
- Fullstack
- Posted
Skills
Must have
- 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 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
Full description
Freelance Senior OR Junior Full Stack Developer – React / Next.Js / Node.Js – Barcelona
Por favor, asegúrese de leer completamente el resumen y los requisitos de esta oportunidad de empleo que se detallan a continuación.
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, xkdbapo 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