Prevent Duplicate API Requests in Angular with Idempotency and HTTP Interceptors

Modern web applications frequently interact with APIs that perform critical operations such as payments, order creation, or data updates. One common problem developers encounter is duplicate requests caused by: users double-clicking buttons unstable internet connections automatic retries browser refreshes during a request Without safeguards, these duplicates can lead to serious issues like multiple charges, duplicated orders, or inconsistent data . To solve this, many modern APIs rely on a conce