Senior Software Engineer

As a Backend Engineer, you'll join our engineering team in Madrid, driving the development of scalable, high-impact backend systems that power our AI-driven products. You don't just implement features - you help shape how AI feels as a product. We're looking for engineers who care about craft, systems design, and user impact, and who enjoy experimenting with new ideas. The best candidates for this role often build side projects, contribute to open source, prototype backend architectures, or experiment with emerging AI capabilities.

What You’ll Do

Build magical AI product experiences - Design and implement fast, intuitive, and engaging experiences that make AI feel natural and useful. Work closely with product and design to explore new interaction patterns, prototype ideas quickly, and turn cutting-edge AI capabilities into simple experiences that millions of users enjoy.

Own backend services end to end- Build and maintain backend services in Python, owning features from design through deployment and monitoring.

Architect scalable backend systems - Design and maintain backend services and APIs that power real-time AI interactions at scale. Ensure performance, reliability, and cost-efficiency as we grow rapidly across markets.

Move fast, ship often - Operate with high ownership and urgency. Prototype quickly, validate with users, and iterate based on real-world feedback. Use modern AI-assisted development tools to accelerate development cycles while maintaining strong engineering quality.

Collaborate across AI, product & growth - Work cross-functionally with AI engineers, product managers, designers, and growth teams to translate experimentation and insights into production-ready systems.

Raise the technical bar - Write clean, maintainable, well-tested code. Contribute to architecture decisions, improve developer experience, and help establish best practices that enable the team to scale.

Think in systems, not just tickets - Anticipate bottlenecks before they happen - whether in performance, UX, cost, or scalability. Proactively improve observability, reliability, and infrastructure as we scale.

Mentor & lead by example - Provide thoughtful code reviews, support other engineers, and help shape a strong engineering culture centered around ownership, craftsmanship, and impact.

What We’re Looking For

+3 years of experience as a software engineer building and shipping production systems used by real users

Strong backend experience in Python, including designing and scaling APIs and services

Hands-on experience building AI agents end-to-end - including tool use, orchestration, evaluation, and shipping them to production

Experience building or integrating AI/LLM-powered features in consumer-facing products

Curiosity about working across the stack, including backend services and APIs that power mobile experiences

Comfort working in fast-paced startup environments with ambiguity and rapid iteration

Strong product intuition: you care deeply about how things feel for users, not just how they are implemented

Experience building systems or applications used by large numbers of users

Ownership mindset: you see problems, take initiative, and drive solutions end-to-end

Interest in AI-assisted software development, modern developer tooling, and experimenting with new ways of building products

Nice to have

Experience with LangGraph and/or LangChain

Working model

This is a hybrid role based in our Madrid office - you’ll combine working from our office and working from home

Equal opportunity

Luzia is an equal opportunity employer. We hire based on what you build and how you think.

Ready to build with us?

Apply via the link below. We read every application