APIs often present subtle yet costly errors, making effective debugging essential for developers. Deep API monitoring is a crucial component of Application Performance Management (APM), providing insights that help identify and resolve issues efficiently. Common debugging pitfalls include Cross-Origin Resource Sharing (CORS) errors, which can impact security and functionality if not properly handled. Tools like Runscope and Moesif Analytics enhance the debugging process by offering robust testing and analytics capabilities, while Zipkin aids in monitoring key API metrics without incurring high infrastructure costs. Understanding these tools and techniques can significantly improve API development and maintenance.