Epsilon is a lightweight tool for monitoring and tracking the performance of Java applications in real time. It supports integration and configuration via Spring, including Spring AOP. Download from: https://www.obix-labs.com Epsilon allows developers to set processing/performance benchmarks for an application, and monitors these in real-time as the application services requests. In cases where these benchmarks are breached, it can issue a notification (e.g. via email or by logging an alert) to one or more destinations. Amongst its many features are: Spring support: Epsilon can be integrated and configured via Spring. Non-intrusive: It can be embedded into applications by employing a Spring AOP interceptor; thus removing the need for explicit references in application code. Simple to embed: Epsilon can also be embedded directly into application code in a manner similar to that used for logging. Statistical and fixed benchmarks: Application performance can be monitored in reference to the historically observed performance/latency of an application. Alternatively monitoring can be based on fixed latency caps. Notifications callback: Email and log alert functionality is provided in the current release; however, users can also implement a simple callback interface to provide custom notification functionality. Highly performant and lightweight: Epsilon will not skew the performance of the monitored application as it functions in an asynchronous and non-blocking manner. Neither will it add unnecessarily to the memory footprint of the monitored application. Historical data: It can be configured to keep a specified amount of historical data, thus making it possible to utilize the collected data for other purposes. Easy to extend Free and open source Java