Many software tools exist to manage knowledge organization systems. Even a simple text editor can be used for small vocabularies. More specialized vocabulary software better supports features such as editing, import, export, quality control and workflows.
See our technical report Software for management of knowledge organization systems (also archived at https://doi.org/10.5281/zenodo.15672523).