Principal Server Engineer at UserWise Services – Spain | Jobyssey

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/HTTP2, 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, including server-authoritative logic and runtime modules on Nakama
Extend and operate Nakama (Heroic Labs) for core game services: authentication, matchmaking, leaderboards, storage, RPCs, and realtime multiplayer
Own database schema design and query performance across PostgreSQL systems, including Nakama's storage layer
Drive horizontal scaling strategy (Nakama clustering, stateless services), 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 against Nakama and supporting services 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 (experience with Nakama's storage layer or CockroachDB a plus)
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 resolution methodology
At least 2 released production projects as a core backend engineer handling live traffic

Important

Practical experience with Nakama (Heroic Labs): custom Go runtime modules (Lua/TypeScript a plus), matchmaker, storage engine, realtime sockets, and running Nakama clusters in production
Hands-on experience with Redis, KeyDB, or Memcached: caching, rate-limiting, state management, including cache stampede mitigation, serialization overhead, and eviction policy design
Solid TDD/BDD judgment and practical load-testing experience (e.g., Artillery), including realtime/socket workloads
Practical GCP/Google App Engine experience: deploying, monitoring, and scaling serverless/container services

Benefits

Market competitive, tax-free USD salaries
Paid Time Off
Annual Performance Reviews

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About the Role

Responsibilities

Requirements