Senior Backend Developer – Node.js

Employment Type: Full-time, Permanent

Location: Madrid, Spain (Hybrid – 3 days on-site)

About the role:

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.

What you'll work on:

• 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...