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!