API Monitor is a Chrome browser add-on that enhances the functionality of the DevTools for developers working on Single Page Applications (SPAs). It provides insights into the usage of browser APIs, including active or passed timeouts, intervals, and eval functions, while also mapping their call stacks to source code locations. Additionally, developers can observe events and property state changes of video or audio media elements on web pages in real-time.

This tool is designed to help developers expedite issue discovery by identifying potential performance bottlenecks and configuration issues. By monitoring API usage, developers can optimize their code and improve overall system performance.