APIs are integral to modern digital infrastructure but also present significant security challenges, necessitating a multi-layered security approach to mitigate threats like DDoS attacks, data breaches, malware, and injections. This comprehensive strategy involves implementing several layers of security, including low-level network security (L3/L4), zero-trust frameworks, service mesh architecture, and robust API authentication and authorization protocols. These layers work in tandem to validate traffic legitimacy, manage certificate lifecycles, enforce centralized authentication policies, and monitor for anomalies using analytics and machine learning. Additionally, policy enforcement is crucial in maintaining security integrity, requiring approval processes to prevent human error and ensuring compliance. This layered security model not only protects sensitive data but also addresses the rising frequency and cost of API attacks, making it essential for organizations aiming to safeguard their API infrastructure effectively.