Slides for a presentation as part of DCMI conference workshop on coli-conc and Cocoda. Abstract of the workshop: Since decades, the Interoperability between knowledge organisation systems (KOS) has been amongst major challenges in German libraries. The KOS landscape of Germany is marked with numerous indexing systems; the majority of libraries use more than one system for indexing, and over 50% of the libraries according to recent statistics use home-grown systems. The project coli-conc addressed this issue and has developed services that enable a uniform access to and an easy sharing of KOS, support computer-assisted mappings between various KOS and facilitate collection, storage and management of both KOS and their mappings on a single platform. This workshop will offer an insight into the service portfolio of coli-conc and demonstrate the functionalities of the mapping tool Cocoda with a hands-on session for the widely-used library KOS like Dewey Decimal Classification, Library of Congress Classification, Library of Congress Subject Headings, Wikidata, and Regensburg Classification. If you are interested in working with other KOS that are relevant to your library or country, please email us and we will be glad to add them to our agenda and data pool.