Senior AI-Native Full-Stack Engineer

Leyton; Sant Cugat del Vallès; On-site; EUR 60,000 - 80,000; Full time

Job summary

Mainloop Barcelona seeks a Full-Stack Engineer to join an AI-native engineering team in Barcelona. You will own end-to-end web products, shape architecture, and collaborate with a Product Owner to deliver robust software built with AI agents.

You will work across a portfolio of projects, moving between products and taking on new challenges as the team grows. The role emphasizes ownership, design, and hands-on coding in a fast-paced environment.

Qualifications

• Own end-to-end production software and architecture.
• Experience with front and back ends of a web app.
• Strong TypeScript skills preferred.
• Experience using coding agents (Claude Code, Cursor, Codex).
• English fluency; Barcelona-based or local relocation possible.

Responsibilities

• Take over a product and own its architecture and release.
• Collaborate with Product Owner to align on roadmap and quality.
• Design with AI agents; balance speed and reliability.
• Work across the growing Mainloop Barcelona team.

Skills

Strong TypeScript

Front-to-back web development

Experience with AI agents

Tools

Claude Code

Cursor

Codex

Playwright

Job description

Mainloop Barcelona seeks a Full-Stack Engineer to join an AI-native engineering team in Barcelona. You will own end-to-end web products, shape architecture, and collaborate with a Product Owner to deliver robust software built with AI agents.

You will work across a portfolio of projects, moving between products and taking on new challenges as the team grows. The role emphasizes ownership, design, and hands-on coding in a fast-paced environment.