Backend / API Engineers

We’re hiring 4 Backend Engineers (Mid, Senior, and Staff levels) to join a high-impact API Platform team building scalable, self-serve infrastructure used by both customers and internal product teams. This is a rare opportunity to join a fast-growing fintech environment where the API is a top business priority and sits at the core of the company’s platform modernisation strategy. Location Madrid (Hybrid: 4 days in office / 1 day remote ) Salary €40K - €90K + bonus + benefits (depending on experience level: Mid / Senior / Staff) About the team You’ll join an API Platform team focused on: - Building a modern, scalable API surface used by external clients and internal teams - Creating self-service capabilities , including instant API credential provisioning - Launching and expanding a new API sandbox environment for clients - Improving performance, observability, reliability, and developer experience - Building foundations for AI-driven workflows via API

integrations (MCP / agentic interfaces) - Supporting platform modernization and service decomposition at scale The API is evolving into a product in itself , with strong visibility across engineering and the business. ️ Tech environment You don’t need to know everything, but experience in similar ecosystems is key: - Backend: Python, Django, REST APIs - Data: PostgreSQL, Redis - Infrastructure: AWS, Docker, Kubernetes, Terraform - Identity / access: IAM concepts (Keycloak or similar is a plus) - Strong engineering fundamentals: system design, OOP + functional design, clean architecture - CI/CD, observability, monitoring, and production ownership mindset What you’ll do Depending on your level, you will: - Design and build scalable backend services and APIs - Own services end-to-end (“you build it, you run it”) - Contribute to architecture decisions via RFC process - Improve platform reliability, latency, and developer experience - Mentor more junior engineers (Senior+ levels) - Help shape a modern platform used at global scale What we’re looking for - Strong software engineering fundamentals (algorithms, design patterns, architecture) - Experience building production-grade distributed systems - Comfortable working in cloud-native environments - Strong communication skills in English (international teams) - Ownership mindset and ability to thrive in ambiguity - Fintech experience is highly valuable Growth & impact - First 3-6 months: contribute to building new platform components from scratch - 12 months: ownership of a key platform area + influence across teams - Clear performance framework and quarterly career development reviews - High visibility role in a strategic engineering initiative About E-Frontiers We are a specialist tech recruitment partner working with leading product companies and fintech organisations across Europe. We focus on connecting strong engineering talent with