Openfire is an open source instant messaging server written in Java using the XMPP infrastructure and using Apache Licensing. System development is now provided by Ignite Realtime. The necessary documentation, plugin and all other requirements are posted on their web site.
Your company can provide your employees instantly with each other, send files and documents to each other via this system very easily and quickly. With the messaging applications integrated into the system (eg Spark application), you can do this free of charge and unlimitedly
As a matter of fact, it is a custom messenger application for you. It is a special software that can only be checked by you and can not be accessed from outside.