ARZ is an extension given to files used by a relational database management system called MySQL. It is an open source system developed by MySQL AB and currently operated by Oracle Corporation.

ARZ are files used by one of the modules of this tool called MySQL Enterprise Backup. This is the internal data of the database engine. These files are not intended to be opened directly by the user. The whole solution allows you to restore databases from backups created by MySQL Enterprise Backup (e.g. in case of damage to the correct database).