About the RoleWe'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+ yearsNice to HaveCI/CD and DevOps experience (GitHub Actions, GitLab CI) plus monitoring/alerting (Prometheus, Datadog)Strong grasp of networking protocols — WebSockets, gRPC/HTTP2, UDP/TCP tuning for low-latency real-time systemsRequirementsResponsibilitiesDesign, build, and maintain Go/Python backend services for live, high-traffic game titlesOwn database schema design and query performance across PostgreSQL systemsDrive horizontal scaling strategy - optimizing CPU/memory footprint and reducing lock contention over vertical scalingProfile and resolve memory leaks, CPU spikes, and deadlocks in productionLead root-cause investigations for performance issues and outages, from detection through resolutionArchitect and maintain in-memory caching/state layers (Redis/KeyDB/Memcached)Design and run load tests to surface breaking points ahead of releaseRequirementsCrucialDeep 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 changesProven 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 deadlocksAt least 2 concrete examples of complex production performance issues or outages, including root cause analysis and resolution methodologyAt least 2 released production projects as a core backend engineer handling live trafficImportantHands-on experience with Redis, KeyDB, or Memcached — caching, rate-limiting, state management, including cache stampede mitigation, serialization overhead, and eviction policy designSolid TDD/BDD judgment and practical load-testing experience (e.G., Artillery)Practical experience with the Nakama framework — custom Go/Lua modules, matchmakers, storage engine, real-time multiplayer socketsPractical GCP/Google App Engine experience — deploying, monitoring, and scaling serverless/container servicesBenefitsMarket competitive, tax-free USD salariesPaid Time OffAnnual Performance Reviews#J-18808-Ljbffr

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