Overview In this role you will own production-grade software across a varied portfolio, partnering with a Product Owner to shape robust, scalable products. You'll operate in an AI-native, agent-driven environment, translating business needs into well-architected solutions. You'll frequently move between projects, influencing architecture, quality, and releases.

This is a hands-on, strategic engineering role with a clear path to growing influence and a prestigious internal certificate upon demonstrated mastery.

Compensaciones / Ventajas Mainloop Barcelona certificate no on-call policy opportunity to work with AI agents and tooling growth through cross-project ownership international exposure clear ownership of product incidents during work hours

Responsabilidades Own the build, architecture, quality and release of a product

Take over and own a product end-to-end after documentation and handoff

Decide what to build next in collaboration with the Product Owner

Work across a portfolio of platforms, agent-native products and internal tooling

Review merges via agent-assisted loop and ensure 100% passing tests





Design with AI agents to balance quality and speed, and judge outputs critically

Mentor teammates and contribute to evolving engineering processes and standards

Contribute to defining the standard stack and participate in architectural governance

Requisitos principales Ownership of production software experience

Front-end and back-end working proficiency

Strong TypeScript or equivalent language proficiency

Experience with tests (unit, end-to-end) and test strategy

Familiarity with coding agents and evaluating agent output

Ability to understand unfamiliar codebases and explain their purpose

Fluent English; Spanish useful

Willingness to work in Barcelona and participate in a team-building environment

Strong judgement and decision-making

Proactive collaboration with Product Owner and teammates

Mentoring and knowledge sharing

TypeScript or equivalent language

Full-stack web development (front-to-back)

Experience with AI agents in development workflows

📌 Full-Stack Engineer - Mainloop (Barcelona)
🏢 Leyton Et Associes
📍 Barcelona