Full-Stack Engineer - Mainloop
LEYTON ET ASSOCIES · Sant Cugat del Vallés, Spain ·
- Category
- Fullstack
Full-stack engineer who owns products end-to-end (architecture, quality, releases) across a portfolio of platforms and internal tooling in an AI-agent-driven environment. Day to day: TypeScript front-to-back development, testing, agent-assisted code review, and collaboration with a Product Owner. Onsite in the Barcelona area.
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 / Beneficios- 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
- 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
- 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