Senior Full Stack Developer (Freelance)

About the role

Netenders is an international e-commerce group based in Barcelona, running several online stores in Europe and North America and developing its own e-commerce CMS. It is looking for a Senior Full Stack Developer (freelance) to collaborate with its in-house tech team on long-term, high-impact projects. The position is freelance with flexible remote work; Barcelona-based candidates are a plus.

Key responsibilities

• Lead the technical evolution and optimization of the multi-brand e-commerce ecosystem.
• Architect scalable React frontends and robust Ruby on Rails backend services.
• Develop core CMS features, especially complex supplier integrations and high-volume data flows.
• Design high-performance APIs and back-office tools for pricing and SEO management.
• Ensure code quality and architectural consistency through expert pull request reviews.
• Work with cross-functional teams to turn business requirements into clean, maintainable code.

Required profile

• Self-driven developer with a consultant mindset who designs solutions with long-term product health in mind.
• Enjoys freelance autonomy while being willing to mentor and share technical expertise.
• Proven track record in e-commerce or complex, data-heavy backend systems.

Required skills

• 5+ years with Ruby on Rails (v5+), including successful version migrations.
• 3+ years building modern interfaces with React.
• Deep understanding of software design patterns and RESTful API architecture.
• Strong proficiency with Docker and Git-based workflows.
• Nice to have: Hotwire Native, ElasticSearch, Redis or Google Cloud Platform.