Scalable backend architecture for an eCommerce site starts with choosing the right tech stack and database strategy. I typically prefer a microservices-based architecture, where each service (like user management, product catalog, payments, etc.) is isolated and can scale independently. For databases, using a combination of relational (like PostgreSQL or MySQL) and NoSQL (like MongoDB or Redis) depending on the use case helps maintain performance and flexibility. Caching frequently accessed data and using CDN for static assets also improves speed and reduces server load.
In addition, implementing asynchronous processing using message queues (like RabbitMQ or Kafka) helps handle tasks like order processing or inventory updates without blocking user actions. I also prioritize observability from the start—centralized logging, performance monitoring, and alerting are key to spotting issues before they grow. Containerization (Docker) and orchestration tools like Kubernetes make scaling and deployment easier, especially during traffic spikes or seasonal sales