- WSO2 ESB is a lightweight, high-performance enterprise service bus that provides comprehensive support for REST, SOAP, and other integration standards. - It supports over 100 pre-built connectors for popular APIs and systems and has coverage of all enterprise integration patterns. - New features in version 4.9 include inbound endpoints that dynamically create listening and polling interfaces, enhanced caching and throttling mediators, and support for Kafka, MQTT, and RabbitMQ messaging.