Abstract Text: The presentation introduces the common portal of Czech libraries, which has been in use for five years. The portal serves as a gateway to collections and services of a number of Czech libraries. Embedded in The Strategy for the Development of Libraries in the Czech Republic, it is a key project in the world of Czech libraries. It was primarily designed to search the collections of all participating libraries and other sources (e.g. bibliographies, databases, collections of law documents, etc.) and provides an online interlibrary loan system. Far from being a mere search platform, the portal performs an educational and curatorial role, our team makes inspiring reading lists and creates web pages on selected topics, drawing on the collections of the participating libraries and other memory institutions. We mostly use open source software (VuFind, Solr, etc.), with the exception of the linking server and the index of foreign sources. Tools developed by the Moravian Library for indexing and data deduplication, as well as all local modifications of VuFind, were developed under an open source license, so they can be used by other libraries and VuFind itself benefits from our improvements where possible. Besides the common development of IT tools, the portal fosters library cooperation on all levels: being involved in a common project, sharing their collections and working together to popularise the portal among library users.