Senior Back-End Engineer (Node.js)

Senior Back-End Engineer (Node.js)

• Salary: 18,700-20,900 PLN/Month
• Warsaw, Poland (Hybrid - 3 days in office, 2 days remote)
• Full-time
• B2B or CoE

We’re looking for a Senior Back-End Engineer to join a fast-growing international tech company focused on building modern, data-driven platforms that power digital transformation in the financial and enterprise sectors.

Requirements:

• Strong experience in building server-side applications using Node.js and Express.js.
• Hands-on experience with API development and integration, particularly with GraphQL or RESTful services.
• Strong knowledge of authentication and authorization mechanisms (OAuth, JWT, session-based).
• Strong experience with databases such as MySQL and  PostgreSQL.
• Experience writing unit tests with tools such as Chai and Mocha.
• Strong experience using Git and version control systems.
• Proficiency in English (both written and spoken).

Nice To have:

• Bachelor’s degree in Computer Science or a related field.
• Experience with cloud platforms (AWS, Azure, or GCP), as well as containerization and orchestration tools such as Docker and Kubernetes.
• Experience with microservices architecture.
• Experience setting up CI for static analysis and test execution.
• Experience developing RAG applications and storing data in vector embeddings.

Key Responsibilities:

• Design, build, and maintain scalable, high-performance server-side applications and RESTful APIs using Node.js and Express.js.
• Guide and supervise the development of key code components to ensure long-term reliability and scalability.
• Integrate with front-end components and third-party services.
• Actively review the codebase, recommending and implementing refinements where needed.
• Write unit and integration tests and optimize performance to ensure high-quality code.
• Collaborate closely with cross-functional teams to define and implement technical solutions.
• Improve system performance, reliability, and long-term maintainability through optimization and best practices.