Full stack monitoring, particularly frontend monitoring, is crucial for maintaining the performance of web applications by providing visibility into client-side operations, allowing developers to swiftly identify and resolve errors. While writing tests for applications is a common practice, it does not entirely eliminate bugs, making monitoring in production essential to prevent customer dissatisfaction and revenue loss due to downtime and poor user experience. Frontend monitoring involves tracking the performance of an app's user interface, ensuring that necessary services and systems are operational, and managing errors and performance issues. Tools like Highlight, Sentry, Rollbar, Site24x7, and Pingdom offer various features such as error detection, real-time monitoring, session replay, and integration capabilities, enabling developers to better understand user interactions, prioritize issues, and efficiently address errors in real-time. These tools help free up resources for development rather than bug fixing, thereby improving the overall efficiency and effectiveness of application management.