Zettel.io provides a solution as to how to manage notes, papers and slips without regard to the tool or editor used to create them. It is a set of repositories, both public and private, that stores and indexes content and does so with the lowest barrier to entry. Notes may be aggregated in one or many repositories called Kasten and ordered in multiple ways by the user. Notes can be connected and along with tagging displayed as a network.

Any private content, will be stored separately and only accessed by the owning user. Content may be shared with other users or made public.