You can find more information and purchase the tool from the developer's official page at Doubley Custom Kontakt Library Creator or via OpenSea. How to Add Non-Player Libraries to Kontakt 7 / 8's Browser
: If your library doesn't appear, check the Libraries tab in Kontakt's Options/Preferences to ensure it isn't hidden. Availability Download File Doubley - Custom Kontakt Library ...
If you are a music producer looking to organize your sample collection, is a specialized utility tool designed to help you create and register your own custom libraries within the Native Instruments Kontakt interface. It is particularly useful for adding "non-Player" or third-party samples to the official Library tab, making them as accessible as factory-installed instruments. You can find more information and purchase the