Company:** X-FLOW
Location: Poland
Employment type: FULL_TIME
Warsaw, Mazowieckie 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 Fullstack Engineer for our flagship project, Happy Color.
Key Responsibilities:
- Design and develop RESTful APIs using PHP/Laravel.
- Build frontend applications using TypeScript/React with a focus on performance and Developer Experience (DX).
- Integrate with external services; define and maintain API contracts.
- Optimize performance, perform profiling, and reduce latency.
- Design database schemas, handle migrations, indexing, and query optimization.
- Contribute to quality assurance: write tests (unit/integration/e2e), conduct code reviews, and automate checks.
- Ensure observability and reliability: implement logs, metrics, alerts, and traces.
- Participate in designing architectural solutions.
Requirements:
- 4+ years of experience with PHP, strong knowledge of Laravel (DI, queues, profiling, REST, modularity).
- 4+ years of experience with TypeScript, strong knowledge of React/Redux Toolkit, routing, build processes, and bundle optimization.
- Databases: PostgreSQL/MySQL, Redis; experience with schema design, indexes, and transactions.
- Message Queues/Buses: Kafka — experience with event-driven integrations.
- Security: OAuth2, JWT.
- Understanding of DDD, SOLID, 12-Factor App methodology, and observability (Prometheus/Grafana, OpenTelemetry).
Nice to have:
- Experience with Golang development.
- Development experience with Ant Design (Antd) 5+.
