eXo Platform is built on open source and open standards. It adheres to the the Java EE stack and leverages many open-source components. The run-time package embeds Tomcat. Data is stored in the file system as well as in a relational database through either JPA or JCR APIs. The chat application also requires MongoDB. Indexing and searching the data are powered by ElasticSearch.
At its heart, a microkernel orchestrates the life cycle of core services, such as managing users and permissions, scheduling jobs, sending out notifications and storing data. Services in the microkernel can be easily overridden, extended or plugged into by custom or additional services.