Senior Java Backend Developer (Node.js / TypeScript)

Wymagania: - API design and system integrations - Event-driven architecture and distributed systems - Asynchronous flows and messaging concepts - Unit and integration testing - Monitoring, logging, troubleshooting, and observability - Java 21+ - Spring Boot 3.x - REST API / OpenAPI - Spring Security / OAuth2 / JWT - Distributed system design experience - Production ownership and incident resolution - Mentoring and technical leadership experience - Technology migration/transformation experience - Ability to influence engineering standards and best practices Mile widziane: - Commercial experience with Node.js and TypeScript - Experience with Express, Fastify, or NestJS frameworks - Knowledge of Kafka or RabbitMQ - Experience with Docker and Kubernetes - Familiarity with GraphQL - Experience with Terraform and Infrastructure as Code - Knowledge of OpenTelemetry and distributed tracing - Experience with Jest or Vitest testing frameworks - Understanding of npm / pnpm ecosystem O firmie: - At Square One Poland we link IT experts with the business. With over 25 years of experience, we specialize in recruitment processes on a global scale. Despite years of experience, we still have a startup DNA and this is our advantage. Our offices are located in London and Warsaw, however, we can reach clients from all over the world, from start-ups to big worldwide corporations. Zakres obowiązków: - Design, develop, and maintain scalable backend services using Java 21+ and Spring Boot 3.x - Build and integrate REST APIs and support integrations with multiple internal and external systems - Work with event-driven and distributed architectures, including asynchronous communication and messaging systems - Support production environments through monitoring, troubleshooting, observability, and continuous improvement activities - Collaborate with architects, frontend developers, product teams, and technical leads in agile delivery teams - Participate in technology transformation initiatives toward Node.js / TypeScript ecosystem - Write unit and integration tests while ensuring high code quality and resilience standards - Contribute to production-grade engineering practices, reliability, and maintainability of services