Voc4cat-tool is a Python package and command-line tool for creating and maintaining SKOS-vocabularies with Excel and GitHub.The voc4cat tool can be run locally but is also well suited for integration in CI-pipelines. It is for example used to maintain the SKOS vocabulary for catalysis voc4cat on GitHub.Its main features include:Conversion between SKOS/turtle representation and Excel/xlsx. The conversion is supported in both directions.Checking of vocabularies. This includes formal validation with SHACL-profiles but also additional checks useful for vocabulary maintenance.Vocabulary metadata management via configuration filesID range allocation for contributors for opaque URIsTransforming of vocabularies between different RDF representations.HTML documentation generation for publishing the vocabulary for example on GitHub pages.