Checking whether a password has been exposed in data breaches is essential for maintaining strong account security. By leveraging the Have I Been Pwned API, developers can create applications that securely check if an inputted password appears in leaked databases without revealing the user's actual password. This is achieved through a k-anonymity model, where a SHA-1 hash of the password is generated and only the first five characters of the hash are sent to the API. The API then returns a list of hash suffixes matching that prefix, allowing the application to safely determine if the password has been compromised while preserving user privacy. Implementing this process in Go involves securing user input, hashing the password, making HTTP requests to the API, and efficiently searching the response for a match—demonstrating practical techniques for integrating robust, real-world security checks into authentication workflows.