About the Role
We're looking for a Principal Server Engineer to own the backend systems powering our live games - services currently supporting 1M+ DAU. You'll be responsible for performance, scalability, and reliability at the core of our infrastructure, working closely with the engineering team on everything from schema design to incident response. Experience: 8+ years
Nice to Have
CI/CD and DevOps experience (GitHub Actions, GitLab CI) plus monitoring/alerting (Prometheus, Datadog)
Strong grasp of networking protocols — WebSockets, gRPC/ UDP/TCP tuning for low-latency real-time systems
Requirements
Responsibilities
Design, build, and maintain Go/Python backend services for live, high-traffic game titles
Own database schema design and query performance across PostgreSQL systems
Drive horizontal scaling strategy - optimizing CPU/memory footprint and reducing lock contention over vertical scaling
Profile and resolve memory leaks, CPU spikes, and deadlocks in production
Lead root-cause investigations for performance issues and outages, from detection through resolution




Architect and maintain in-memory caching/state layers (Redis/KeyDB/Memcached)
Design and run load tests to surface breaking points ahead of release
Requirements
Crucial
Deep Go & Python expertise — language internals, execution models, and performance tuning (goroutine management, GC tuning, zero-allocation techniques)
Strong PostgreSQL fluency — scalable schema design, query plan analysis, index strategy optimization, with real examples of resolving bottlenecks via data layout or query architecture changes
Proven experience scaling systems supporting 350k+ DAU, with a horizontal-scaling-first philosophy (efficient serialization/deserialization via Protobuf/MsgPack, reduced lock contention)
Hands-on profiling experience — identifying and resolving memory leaks, CPU spikes, and deadlocks
At least 2 concrete examples of complex production performance issues or outages, including root cause analysis and r

📌 Principal Server Engineer (Madrid)
🏢 UserWise Services
📍 Madrid