In our interconnected digital ecosystem, API security is paramount. Traditional static password systems once used for API authentication, face vulnerabilities to cyber threats. This paper explores Natural Language Understanding (NLU) as a tool for dynamic password solutions, achieving 49.57% accuracy. It investigates GPT-2 for dynamic password generation and innovative NLU-based verification using a set of specific criteria and threshold adjustments. The study highlights NLU’s benefits, challenges, and prospects in enhancing API security. This approach is a significant stride in safeguarding digital interfaces amidst evolving Cyber Security threats. Keywords: Cyber Security, Authentication, API Security, Generative AI, Dynamic Passwords, Passwords Verification, NLU