Senior Full Stack Developer - Freelancer

Netenders; España; Remote; EUR 83,000 - 124,000; Full time

Job summary

Netenders, based in Barcelona, seeks a Senior Full Stack Developer (Freelance) to collaborate with the in-house team on long-term e-commerce CMS projects. You will architect scalable Rails backends and React frontends, focusing on supplier integrations and high-volume data flows.

You will work autonomously in a freelance capacity, with flexible remote options. Prior mentoring and sharing expertise to help internal teams grow are valued, alongside strong communication of complex technical

Qualifications

• 5+ years of experience with Ruby on Rails (v5+), including migrations.
• 3+ years of professional experience building modern interfaces with React.
• Deep understanding of software design patterns and RESTful API architecture.
• Proven track record in e-commerce or handling complex, data-heavy backend systems.
• Strong proficiency with Docker and GIT-based workflows.

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 focusing on 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-level pull request reviews.
• Collaborate with cross-functional teams to translate business requirements into clean, maintainable code.

Skills

Software design patterns

RESTful API architecture

Autonomy & self-management

Clear communication of complex ideas

Tools

Ruby on Rails

React

Docker

Git

Elasticsearch

Redis

Google Cloud Platform

Job description

Netenders is an international e-commerce group based in Barcelona, operating several leading online stores in Europe and North America. As we continue to grow and innovate, we are developing our own cutting-edge e-commerce Content Management System (CMS) to revolutionize the online shopping experience across our brands. We are looking for a Senior Full Stack Developer (Freelance) to collaborate with our in-house tech team on high-impact, long-term projects.

This is a freelance position, with flexible remote work (Barcelona-based candidates are a plus).

Your Role:

• Leading the technical evolution and optimization of our multi-brand e-commerce ecosystem.
• Architecting scalable React frontends and robust Ruby on Rails backend services.
• Developing core CMS features, specifically focusing on complex supplier integrations and high-volume data flows.
• Designing high-performance APIs and back-office tools for pricing and SEO management.
• Ensuring code quality and architectural consistency through expert-level pull request reviews.
• Collaborating with cross-functional teams to translate business requirements into clean, maintainable code.

About you:

You are a self-driven developer with a consultant mindset. You don’t just write code; you design solutions that consider the long-term health of the product. You enjoy the autonomy of freelance work but understand the importance of mentorship and sharing your technical expertise to help internal teams grow.

Requirements:

• 5+ years of experience with Ruby on Rails (v5+), including successful version migrations.
• 3+ years of professional experience building modern interfaces with React.
• Deep understanding of software design patterns and RESTful API architecture.
• Proven track record in e-commerce or handling complex, data-heavy backend systems.
• Strong proficiency with Docker and GIT-based workflows.
• Ability to work autonomously and communicate complex technical concepts clearly.
• Nice-to-have: Experience with Hotwire Native, ElasticSearch, Redis, or Google Cloud Platform.

We celebrate diversity and want our team to reflect this inclusively. At Netenders , we are committed to equal employment opportunities regardless of ethnicity, religion, gender, national origin, sexual orientation, age, marital status, disability, gender, gender identity, or gender expression