Based on the keywords provided, you are likely looking for a feature description for a utility that allows users to add third-party or custom instrument libraries into Native Instruments Kontakt, especially when the standard "Add Library" button is missing or non-functional (common with "non-Kontakt Player" libraries).
Since this is not an official Native Instruments product, you won’t find it on their website. Look for reputable audio production communities such as: kontakt add library tool download
Native Instruments changed the rules. As of Kontakt 6.2+, third-party libraries must be registered with Native Access or loaded via the Files tab. The “Add Library” workaround no longer works. This tool is primarily for Kontakt 5 and earlier versions. Based on the keywords provided, you are likely