A cartridge is a container for a framework, load balancer or data management system. You can add a cartridge in a platform as a service (PaaS) for scalability. In WSO2 Private PaaS, cartridge runtimes create service runtimes. For example, if you want to have a Enterprise Service Bus (ESB) runtime, you can use a WSO2 ESB cartridge to get the runtime to deploy a mediation flow. A cartridge can be fully configured with all the software and configurations, or zero configured where the cartridge user can install and configure what they want. For more information, see Cartridge and for information on all the properties that you can define in a cartridge definition JSON, see the Cartridge Resource Definition.