Senior Backend Engineer (Go)

X-FLOW is a mobile game development company established in 2018. We gained recognition after the release of Happy Color, the most popular digital coloring book and one of the most successful ad-driven mobile apps in the world. We are currently looking for a Senior Backend Engineer (Go) for our flagship project, Happy Color.Key Responsibilities:• Design and develop microservices in Go (REST/gRPC), public and internal APIs.• Integrate with external services, develop contracts.• Optimize performance, profiling, reduce latency, and scale systems.• Design database schemas, perform migrations, indexing, and query optimization.• Work with PostgreSQL/MySQL, Redis, Kafka/NATS and event-driven integrations.• Implement and maintain CI/CD, cloud infrastructure (AWS) with Docker/Kubernetes.• Ensure quality: writing tests (unit/integration/e2e), code reviews, automation of checks.• Ensure observability and reliability: logging, metrics, alerting, tracing.• Participate in architectural design, RFCs/ADRs.Requirements:• 3+ years of commercial development experience, including 3+ years with Golang.• Proficient in Go: context handling, concurrency (goroutines/channels), profiling (pprof), gRPC/REST, generics, modularity.• Strong understanding of backend architecture, API design, microservices, and distributed systems.• Databases: PostgreSQL/MySQL, Redis; design, indexing, transactions.• Queues/Buses: Kafka/NATS — experience in designing event-driven integrations.• Experience with search technologies such as OpenSearch would be a plus.• CI/CD: GitLab CI, feature flags, migrations, blue-green/rolling deployments.• Testing: Go testing/testify, integration/e2e.• Security: OAuth2, JWT.• Understanding of DDD principles, SOLID, 12-factor methodology, observability (Prometheus/Grafana, OpenTelemetry).• Russian - C1/higher, English - B1.Nice to have:• Experience with Python and/or PHP.• Experience with TypeScript, JavaScript and React.• Experience with OpenSearch.• Data architecture: CQRS/Event Sourcing, idempotency, deduplication.• Experience building BFFs, WebSockets.• Feature flags, experiments/A-B testing, product metrics.Technology Stack (Primary):• Backend: Go, gRPC/REST, PostgreSQL, Redis, Kafka.• DevOps: GitLab CI, Docker, nice to have: Kubernetes, AWS, Helm.• Observability: Prometheus, Grafana, Loki, OpenTelemetry, Sentry.• Search: OpenSearch.What We Offer:• Competitive salary and benefits package.• Opportunity to work with a talented and passionate team in a creative and dynamic environment.• Flexible working hours and remote/office work options.• Career growth and professional development opportunities.• A fun and inclusive company culture that celebrates diversity and creativity.Join us and let’s create great content together!