Senior Backend Engineer (AI)

TL;DR

Senior Backend Engineer (Node.js/TypeScript/Python): Building and scaling AI-driven SaaS agents for business automation with an accent on scalable architecture, distributed systems, and AI integration. Focus on designing high-performance backend services, managing technical debt, and bringing LLM capabilities into production environments.

Location: Hybrid (Barcelona or Madrid). Must be eligible to work in Spain.

Company

An AI-first SaaS company building AI Agents that help businesses deliver exceptional user experiences.

What you will do

• Translate product requirements into clear technical strategies and execution plans.
• Design and evolve scalable systems to handle traffic, data complexity, and AI-driven use cases.
• Write clean, maintainable code and continuously improve engineering practices and quality.
• Mentor team members through code reviews, collaboration, and technical guidance.
• Partner with Product teams to align technical decisions with business goals and user impact.
• Manage technical debt by creating structured, measurable, and actionable repayment plans.

Requirements

• Proficiency in modern backend stacks: Node.js, TypeScript, and Python.
• Experience with relational databases (Postgres, MySQL) and NoSQL systems (Redis, MongoDB).
• Strong knowledge of distributed systems, cloud infrastructure (GCP, AWS, or Azure), and Domain-Driven Design (DDD).
• Proven experience building and operating high-scale web applications in production environments.
• Fluency in both English and Spanish.
• Eligibility to work in Spain.

Nice to have

• Experience with AI/ML APIs, vector databases, or data pipelines.

Culture & Benefits

• Hybrid work model with flexibility between remote work and the Barcelona office.
• Flexible working hours and 26 paid days off per year plus birthday leave.
• Annual budget for professional development and training.
• English and Spanish language lessons and transportation tickets.
• Collaborative environment focused on ownership, autonomy, and high performance.

Hiring process

• HR screening to validate culture fit and experience.
• Interview with the Director of Engineering regarding technical perspective and approach.
• Technical interview with the team focusing on system design and architecture.
• Final meeting with the founders.