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Full-Stack Engineer - Mainloop

Barcelona (Sant Cugat del Vallès), ES💼 Full-time🗓 2026-09-07 → 2026-09-11

Core

Own end-to-end production software products for businesses across 15 countries, transforming prototypes into reliable, long-term solutions using AI-native engineering methods.

Role type

Full-Stack Engineer (Product Owner & Architect)

Builds

Production automation software, agent-native products, and internal tooling for professional services.

Domain

Professional services automation, AI-native software engineering, multi-country enterprise systems.

Deliverable

production ML models | product features

Required skills

Full-stack development, system architecture, AI agent orchestration, code review and quality judgment, product ownership, test strategy (unit, smoke, E2E), specification design.

Preferred skills

Experience with coding agents (Claude Code, Cursor, Codex), building with AI from scratch, navigating large codebases, strategic decision-making.

Technologies

Claude Code, Cursor, Codex, Playwright, CI/CD pipelines, AI model gateways.

Responsibilities

Take ownership of existing products and drive their evolution; design system architecture and specifications for AI agents to implement; review and validate AI-generated code for correctness; ship products with 100% test coverage and evaluation metrics; collaborate with Product Owners to translate business needs into technical specs.

Seniority

Mid-to-Senior (explicitly hiring for 1 Senior seat and 4 Junior seats)

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