? We’re building Mainloop AI in Barcelona: a new AI-native engineering team focused on building production-grade software with coding agents from day one.
Mainloop AI is being created to build and scale software products that automate professional-services work across roughly 15 countries. The team will work on internal platforms, agent-native products and tools that move beyond prototypes into software businesses actually depend on.
This is not a traditional engineering team adding AI on top. Mainloop AI is being built AI-native from the first commit: engineers will work with coding agents such as Claude Code, Cursor, Codex or similar as part of the core development process, with a strong focus on architecture, judgement, testing and production quality.
We’re now hiring the first Full-Stack Engineers to join Mainloop AI in Barcelona:
? 4 junior positions
? 1 senior position
What you’ll do
You’ll work on real products alongside a Product Owner. Each product is owned by a two-person team: the PO leads the relationship with the business,
the needs and the roadmap; you lead the architecture, quality, build and release.
Your responsibilities will include:
Taking ownership of products used by teams across different countries.
Turning prototypes into robust, maintainable, production-ready software.
Designing architecture and making technical decisions with long-term impact.
Working with AI coding agents as a central part of the development process.
Reviewing, validating and improving code generated by agents.
Ensuring quality through unit, smoke and end-to-end testing.
Evolving existing products and contributing to new ones.
Helping define the technical standards and ways of working of a new team.
Here, AI does not replace engineers — it gives them more leverage. The value is in your technical judgement, your ability to define what should be built, and your ownership of products in production.
What we’re looking for
We don’t expect you to tick every box from day on
📌 Full Stack Engineer (San Cugat del Vallés)
🏢 Leyton
📍 San Cugat del Vallés
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