Where Complex Event Processing meets Open Source: Esper & NEsper Highly-available via EsperHA. Reporting, charting and query by EsperJDBC. Embed mainstream CEP in your products and deployments: Learn about our licensing options. Event Stream Intelligence with Esper and NEsper Esper is a component for CEP and ESP applications, available for Java as Esper, and for .NET as NEsper.Esper and NEsper