About X-FLOW
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.
