The candidate should have hands-on experience using Node.js to build backend systems that can scale with growing traffic and data. This includes writing efficient, non-blocking code using the event-driven architecture of Node.js, designing modular services, and optimizing performance for large-scale applications.

2. Hands-on experience with API development & request handling (REST) :

The developer must be proficient in designing and developing RESTful APIs, including defining endpoints, HTTP methods (GET, POST, PUT, DELETE), request/response structures, status codes, authentication, and validation. Experience handling large volumes of API requests reliably and securely is essential.

3. Ability to handle high-concurrency systems and parallel client requests :

The role requires experience building systems that can process thousands of simultaneous client requests without performance degradation. This includes efficient use of asynchronous I/O, event loops, worker threads, connection pooling, and strategies to avoid bottlenecks under heavy load.

4. Experience designing multi-tenant systems with client isolation :

The candidate should understand how to design applications that serve multiple customers (tenants) from a single system while ensuring data isolation and security. This includes tenant-aware architecture, database-level isolation (schema or row-level), request-level tenant identification, and access control mechanisms.

5. Knowledge of batching and bulk processing logic :

The developer should be able to implement batching techniques to process large volumes of data efficiently. This includes grouping multiple operations into batches to reduce network calls, improve throughput, manage rate limits, and optimize database writes or external API interactions.

6. Experience handling CDC (Change Data Capture) events and event-driven workflows :

The role requires exposure to systems that react to data changes in real time using CDC. This includes consuming events from message brokers or streams, processing database change events, and building event-driven workflows that trigger downstream services reliably and in near real time.

7. Strong understanding of asynchronous programming, retries, idempotency, and fault tolerance :

The candidate should deeply understand async programming concepts such as promises, async/await, callbacks, and event loops. They must know how to implement retry mechanisms, ensure idempotent operations, and design systems that gracefully recover from failures without data duplication or loss.

8. Good understanding of database consistency, locking, and transactions :

The developer must understand how databases maintain consistency, including transaction management, isolation levels, row/table locking, and concurrency control. This knowledge is critical for avoiding race conditions, deadlocks, and data integrity issues in high-traffic systems.

9. Experience with distributed systems :

The role requires familiarity with distributed system concepts such as service-to-service communication, eventual consistency, load balancing, horizontal scaling, network failures, and coordination between multiple services running independently.

10. Exposure to cloud platforms (AWS / GCP / Azure) :

The candidate should have experience deploying and running Node.js applications on cloud platforms. This includes working with cloud services such as compute, storage, networking, managed databases, queues, serverless functions, and understanding cloud security and scalability practices.

11. Knowledge of observability, logging, and monitoring :

The developer should know how to instrument applications for observability by implementing structured logging, metrics, and distributed tracing. Experience with monitoring system health, detecting performance issues, debugging production problems, and setting up alerts is essential for maintaining reliable services.