Trustworthiness of data repositories is a key factor enabling Open Science. It is critical for repository end users to be able to find and access data. CoreTrustSeal (CTS) is well recognised as a community driven, domain agnostic, core certification framework. This workshop will showcase relevant initiatives, demonstrate how they are organised, the activities involved, and identify good practices. The workshop is primarily aimed at individuals with an interest in different regional, national and thematic initiatives/approaches to CTS certification, as well as those with a general interest in the management and certification of data repositories.