As well as holding metadata and links to the offsite data, CKAN can provide secure storage for the data itself. When creating the dataset or resource, you can either link to data hosted elsewhere, or upload it in the same action as registering it on CKAN.
Data can be stored in any format. For structured data, e.g. when a spreadsheet is uploaded, CKAN provides a rich API for the data itself, allowing users to query, retrieve and use data instantly from datasets in CKAN without needing to download or process it first. CKAN’s own visualisation tools use this to display data previews, graphs and visualisations of the data on the dataset resource page.