WSO2 ESB is the one stop shop for your integration requirements.
You need to send a message request of format1 to a back-end that accepts messages of format2? Worried about data format transformations? WSO2 ESB will cover this for you with its data transformation capabilities.
You need to send different requests of users to different back-ends? Worried about how to route these messages? WSO2 ESB will cover this for you ,with its message routing capabilities.
Need to make sure that your service is not available to public and its secured? WSO2 ESB has this covered with its service mediation capabilities.
This is just a glimpse of what WSO2 ESB has in store.. How about data transportation and service hosting? Yes these too are WSO2 ESB capabilities..
Check out http://wso2.com/library/articles/2017/07/what-is-wso2-esb/ written by Samisa Abeysinghe (Chief Engineering and Delivery Officer at WSO2) and find out more!