Full stack engineer

MarsBased

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Location: Spain
Job Type: full-time
Salary: Unknown
Posted: February 21, 2026

Job Description

MarsBased is a boutique development consultancy based in Barcelona, focused on delivering high-quality, end-to-end web and mobile applications. We build solutions primarily using Ruby on Rails, React, and JavaScript, and strongly believe in remote work, clean code, and quality over quantity.

We’re looking for a Full Stack Engineer with solid experience in Node.js, React, and Next.js to join our Martian crew.

At MarsBased, you’ll work with a small, senior, and highly collaborative team that values autonomy, transparency, and craftsmanship. We care about doing things the right way, with clean architectures, thoughtful design, and deep, focused work (not endless meetings). If you love elegant code, solving real problems, and being part of a kind, experienced, and fully remote team, your next orbit might just be with us.

What you’ll do

Build and maintain modern, scalable web applications using Node.js, React, and Next.js.
Collaborate closely with clients and teammates in a friendly, remote-first environment.
Contribute to architecture decisions and ensure clean, maintainable codebases.
Use AI-assisted coding tools to improve development speed and quality.
Help us refine our internal tools, workflows, and development culture.

General skills

Clear and professional written and verbal communication with internal teams and clients/stakeholders.
Enthusiastic and positive approach to new challenges; ability to quickly assimilate new information and processes.
Ability to work independently, demonstrate strong self-management skills in a remote environment, and take ownership of projects.
Excellent attention to detail and commitment to high-quality output.
Proactive & able to work alone on projects managed by you.
Fluency (written and spoken) in English and Spanish is required.
Experience using AI agents or AI code editors (e.g., Cursor, Copilot) to assist in coding tasks.

Technical Skills

5+ years of production experience building Node and React applications.
Production experience with Next.js, the App Router, and Server Components is required.
Strong command of JavaScript and TypeScript.
Solid understanding of relational databases and SQL.
Experience with backend technologies like Ruby on Rails & Python is strongly valued.
Experience with React Router or Remix is a plus.
Production experience deploying and maintaining Node.js applications.
Comfortable working with Docker and containers in both development and production environments.
Experience with testing frameworks such as Jest or Cypress.
Ability to write self-documented code. We expect you not only to solve problems but also to write code that is easy to understand.
Ability to leverage AI coding assistants (e.g., GitHub Copilot, Gemini Code Assist, or Cursor) to enhance productivity, accelerate boilerplate generation, improve code explanations, and aid in debugging and testing.

Benefits

Competitive Pay: Your contribution deserves to be valued.
Work your way: We’re an office-less company. Home office or coworking space. You choose what works best for you.
Flexible hours: Set your own schedule and work when you’re at your best.
Awesome Teammates: You’ll be surrounded by kind, smart, and fun people who love what they do.
Modern Tools: We use up-to-date tech and innovative methods to make work smoother (and more enjoyable).
Open & Honest Culture: We enforce transparency, quality, and teamwork.
Team Fun: From casual catch-ups to team events, we make sure there’s always time to laugh and connect. It’s not always about work.

Location

This position is only open to applicants residing in Europe who hold a valid work permit authorizing employment in the region.

Why MarsBased?

Join us and help us build software that lasts, from Mars, or anywhere you call home ❤️

🎯 Who is this job for?

This role is ideal for a Senior Full Stack Engineer with 5+ years of production experience in Node.js, React, and Next.js (App Router & Server Components). It suits someone who values clean architecture, autonomy, and remote collaboration, and is comfortable owning projects end-to-end, from database design (SQL) to frontend implementation and deployment with Docker. You should be confident writing maintainable, well-tested code, leveraging AI coding assistants effectively, and contributing to architectural decisions in a small, senior team environment.

💬 Potential Interview Questions

How would you architect a scalable full-stack application using Node.js, React, and Next.js (App Router)?
I would separate concerns between API routes, server components, and client components, leveraging Next.js App Router for hybrid rendering. Clear domain boundaries, modular services, and well-defined data access layers ensure scalability and maintainability.
What are the key differences between Server Components and Client Components in Next.js, and when would you use each?
Server Components reduce bundle size and improve performance by rendering on the server without sending unnecessary JavaScript to the client. Client Components are used when interactivity, state, or browser APIs are required.
How do you structure a Node.js backend for long-term maintainability?
I follow layered or hexagonal architecture principles, separating controllers, services, and repositories. Strong typing with TypeScript, centralized error handling, and consistent validation patterns improve clarity and testability.
How would you design and optimize a relational database schema for a production application?
I start with normalized schema design, define proper foreign keys and indexes, and optimize based on query patterns. I monitor slow queries and refine indexing strategies as the system evolves.
Describe your approach to deploying and maintaining Node.js applications in Dockerized environments.
I create optimized multi-stage Docker builds, manage environment variables securely, and ensure health checks are configured. CI/CD pipelines automate builds, tests, and deployments for consistent releases.
How do you ensure code quality and reliability in a remote-first engineering team?
I rely on strong pull request reviews, automated testing with Jest or Cypress, linting, and clear documentation. Async communication and well-scoped tasks help maintain alignment without excessive meetings.
What strategies do you use to optimize performance in a Next.js application?
I leverage server-side rendering or static generation where appropriate, minimize client-side JavaScript, implement caching strategies, and monitor Core Web Vitals to guide improvements.
How do you effectively use AI coding assistants like Copilot or Cursor in your workflow?
I use AI for scaffolding, boilerplate generation, refactoring suggestions, and writing tests, while carefully reviewing outputs for correctness and security. AI enhances productivity but does not replace engineering judgment.
How would you integrate a Ruby on Rails or Python service into a Node.js-based architecture?
I would communicate via REST or message queues, ensuring clear API contracts and authentication mechanisms. Proper documentation and versioning maintain interoperability between services.
How do you balance autonomy and collaboration in a fully remote, senior-level team?
I take ownership of features end-to-end while maintaining transparent communication through detailed updates and documentation. I proactively seek feedback and contribute to architectural discussions to uphold shared engineering standards.

📋 Job Summary

MarsBased is a Barcelona-based boutique development consultancy building high-quality web and mobile applications with a strong remote-first culture. We’re hiring a Full Stack Engineer (100% Remote, Europe) to develop scalable products using Node.js, React, Next.js (App Router & Server Components), and TypeScript, contributing to clean architectures and thoughtful technical decisions. You’ll collaborate with senior teammates and clients, leverage AI-assisted coding tools, and help shape robust, maintainable systems in a calm, meeting-light environment. Join MarsBased to work with a kind, experienced team that values craftsmanship, flexibility, and building software that truly lasts.