Building Scalable and Secure APIs with GraphQL

GraphQL provides a flexible alternative to REST for building APIs, but scaling and securing GraphQL APIs can introduce unique challenges. How can developers ensure that their GraphQL APIs remain performant as the application grows? Discuss strategies for optimizing query performance, managing nested queries, and preventing over-fetching of data. What are the best practices for securing GraphQL APIs against common attacks such as query batching, denial-of-service (DoS), and unauthorized access to sensitive data? How can developers implement rate limiting and authentication mechanisms to ensure both scalability and security?