Downloading VDDK is free. Using it to write your own tools is also free. , the moment you distribute a commercial application that bundles VDDK, you must sign a VMware Technology Partner Program agreement. For internal scripts and backup appliances, you are fine.
Once logged in, hover over “Products” in the top navigation bar and click “A-Z Product List.”
If prompted to accept the End User License Agreement (EULA), read and accept it.
The kit provides a collection of C libraries, code samples, and utilities designed to help you create, manage, and access VMware virtual disk storage (VMDK files). It is primarily used by third-party backup software—such as Acronis Cyber Protect or IBM Cloud Paks —to perform off-host backup processing without impacting the performance of running virtual machines.