APIs are used to integrate information from outside sources into applications, simplifying coding and making interactive applications easier. However, APIs have become a preferred target for hackers due to their broad usage and exposure of valuable data. Common API security risks include Cross-site scripting (XSS) Attacks, Injection Attacks, Distributed Denial-of-Service (DDOS) Attacks, Man in the Middle (MITM) Attacks, Credential Stuffing Attacks, among others. To secure APIs, developers should follow best practices such as enabling only necessary protocols and features with least privileges, maintaining an inventory of APIs, sanitizing user-supplied information, enforcing strong API authentication and authorization, encrypting traffic, and segmenting network traffic. Controlling the flow of information coming to APIs is vital, making rate and payload size limiting a cornerstone of security posture. Monitoring APIs' performance, availability, and changes is crucial for security monitoring. Securing Twilio accounts involves using strong passwords, multi-factor authentication, secure authentication tokens, and protecting API keys. Harden applications by following secure development lifecycle, disabling unnecessary features, and validating incoming requests. Finally, securing resources with visibility into Twilio applications and monitoring event logs can help prevent security breaches.