Build AI Products. Own Them. Shape the Future of Engineering in Barcelona.

Full-Time | Permanent

Location: Barcelona, Spain

Open to candidates across North America (United States & Canada)

Relocation to Barcelona, Spain is required

Visa sponsorship and relocation support available

Target Start Date: January 2027 (or as soon as work authorization is completed)

About Mainloop

Mainloop is a new AI-native engineering team based in Barcelona, built from the ground up inside an established international group.

We combine the energy of a startup with the stability, customers, and general reach of an organization that has been operating for decades.

Our mission is to build software that transforms how professional-services businesses operate by automating complex processes, reducing administrative work, and creating products that teams rely on every day.

The group has operated a technology lab in Casablanca for more than eight years. Barcelona is our second technology hub, created to be closer to the businesses we support and built with AI at the center from the beginning.

We are building the team now, and this is an opportunity to help shape how modern engineering teams work.

The Opportunity

We are hiring Full-Stack Engineers at two levels:

We are looking for early-career engineers who are curious, ambitious, and excited about the future of AI-assisted software development.

You do not need years of production experience. What matters is:

- You can build working applications.
- You enjoy learning quickly.
- You have experimented with AI coding tools.
- You want to become exceptional at building software with modern AI workflows.

We are looking for an experienced engineer who has owned production software and can help define architecture, engineering standards, and development practices as the team grows.

You will help shape how products are built, maintained, and scaled.

What You Will Do

As a Full-Stack Engineer at Mainloop, you will own products from development through long-term success.

You will:

- Build and maintain software products used by teams across multiple countries.
- Partner with Product Owners to translate business needs into technical solutions.
- Design scalable architectures and make strong engineering decisions.
- Develop frontend and backend applications.
- Review, improve, and maintain existing codebases.
- Use AI coding agents to accelerate development while maintaining quality.
- Build features, write tests, and ship reliable software.
- Own production quality and continuously improve the products you support.
- Help define engineering practices, tools, and standards as the team grows.

AI-Native Engineering Environment

Mainloop is not a traditional engineering team that added AI tools afterward.

AI is part of how we build from day one.

You will work with:

- AI coding agents such as Claude Code, Cursor, Codex, and similar tools.
- Automated code review processes.
- Modern testing and deployment practices.
- Shared engineering patterns across our products.

The goal is not simply to write code faster.

The goal is to become better engineers by spending more time on:

- Problem solving
- Quality
- Technical judgment

What We Are Looking For

We are looking for engineers who enjoy ownership and building things that matter.

You may be a strong fit if you have:

- Experience building web applications across frontend and backend.
- Strong understanding of software engineering fundamentals.
- Experience with modern development frameworks and technologies.
- Ability to understand existing codebases and improve them.
- Strong problem-solving skills and attention to quality.
- Ability to communicate clearly in English.

For the Senior Engineer role, we are looking for:

- Experience owning production applications.
- Ability to make architecture decisions.
- Experience mentoring or guiding other engineers.
- Strong judgement around technical trade-offs.

For the Junior Engineer role, we are looking for:

- Ability to build a complete working application.
- Personal projects, internships, university projects, or early professional experience.
- Curiosity and motivation to grow quickly.
- Experience experimenting with AI coding tools.

Technology & Engineering Practices

We believe strong engineering comes from good systems.

- Automated testing.
- Code quality and review processes.
- Clear ownership.

We use standards where

📌 Full Stack Engineer (Barcelona)
🏢 Leyton
📍 Barcelona