Backend Engineer w Warszawa, Polska

Senior Back-end Developer (https://jobeax.com/link/JSd7UYCSg572jJDY / TypeScript) About the Role We are looking for a Senior Back-end Developer to join our client's team. You will architect and implement robust backends, interacting with various data stores and third-party APIs to support real-time automated decision-making. Working in an agile, multinational environment, you'll have huge creative freedom and ownership over your projects while collaborating closely with Product Managers, Senior Engineers, and Architects. Key Responsibilities Architect and implement backends and their interactions with data stores and APIs. Support reliable databases and APIs for real-time automated decision-making. Deploy software using industry-standard tooling like Kubernetes clusters and AWS Lambda functions. Investigate and resolve production issues, implementing timely fixes to minimize user impact. Focus heavily on security, following Defense in Depth principles and ensuring containers are secure. Implement robust automated test suites (unit, integration, and e2e) to maintain a low failure rate. Leverage AI-assisted development tools (such as Cursor, Claude Code, or Devin) as a core part of your daily workflow to accelerate speed and quality. Requirements 5+ years of hands-on experience with https://jobeax.com/link/JSd7UYCSg572jJDY, JavaScript, and TypeScript. Practical knowledge of at least one relational database system (e.g., PostgreSQL, MySQL, or SQL Server). Adept with microservices and system design patterns. Experience implementing the test pyramid and utilizing good security practices. Strong sense of ownership, independence, and the ability to clearly convey ideas across technical and non-technical teams. Comfort with AI-assisted development tools as a core part of your setup. Good command of English (written and spoken). Availability in the afternoons/evenings for occasional alignment with multinational teams across time zones. Tech Stack & Tools Backend: https://jobeax.com/link/JSd7UYCSg572jJDY, TypeScript, https://jobeax.com/link/wGBLasCtsmGJlvEi Cloud & DevOps: Docker, Kubernetes, AWS (Fargate, Lambda) Testing: Automated software testing (unit, integration, e2e) AI Tools: Cursor, Claude Code, Devin (autonomous AI engineer) Nice-to-Haves Familiarity with Docker/Kubernetes/AWS deployment processes. Experience with profiling and performance optimization. Experience giving high-quality feedback during code reviews.