The Internet of Things (IoT) is revolutionizing connectivity across various devices, with projected investments surpassing $1 trillion by 2026, but it also introduces significant cybersecurity challenges. APIs are essential for the scalability and security of IoT, facilitating data exchange and enabling interoperability among diverse devices, yet they also present vulnerabilities that can be exploited if not properly secured. Addressing these challenges involves devising a robust IoT API security strategy that includes encryption, authentication, and secure coding practices, alongside the use of API gateways and advanced technologies like machine learning, blockchain, and Zero Trust architecture. Such measures are crucial for safeguarding data during transmission and ensuring the integrity of IoT networks, which are susceptible to threats like DDoS attacks and data breaches. The evolving landscape of IoT demands continuous enhancement of API security measures to protect sensitive information while supporting the scalability and real-time performance essential for applications like autonomous vehicles and wearable medical devices.