Backend Developer

We’re hiring on behalf of a established European fintech opening a new Madrid engineering hub, as part of a broader expansion across the continent. This is a hands-on senior role with real ownership, not a ticket-execution position. You’ll join a small, pragmatic backend team building and maintaining the core data infrastructure that enterprise financial clients depend on daily., * A Core Data API with 40+ endpoints serving live financial data to enterprise clients, currently in its final development phase

• Approximately 30 microservices, including ongoing ownership of stability and performance
• An active migration from MySQL to MongoDB and Redis
• A stack that includes plain JavaScript, gRPC, Kafka, and an on-premise Kubernetes cluster across dev, UAT, and production environments

• 5+ years of hands-on Node.js backend development
• Experience designing and architecting production-grade systems, not just implementing assigned tasks
• Strong SQL fundamentals; MongoDB or Redis experience is a plus
• Comfortable owning deployments, monitoring, and incident response alongside development work
• Solid PR-based workflow and code review experience
• Able to hit the ground running on a complex codebase with minimal onboarding support
• Comfortable in a distributed team setup (most of the current team is based in Germany)

Familiarity with gRPC, Kafka, Docker, Kubernetes, or financial data platforms is a genuine advantage., Candidates must be based in Madrid or willing to relocate, and must be eligible to work in Spain indefinitely without sponsorship. Please submit your CV in English.

50,000 to 75,000 EUR gross per year depending on experience., * Direct ownership of advanced technical initiatives in a product that is actively shipping

• Pragmatic engineering culture: Claude Code already approved, Copilot in evaluation
• Small team growing from 5 to 8-9, with real influence on technical decisions
• Hybrid setup: 3 days on-site in Madrid, plus up to 4 weeks per year working from another location
• Competitive holiday entitlement and employee assistance programme