Zim is "a graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images."
Pages are stored in a folder structure, like in an outliner, and can have attachments. Creating a new page is as easy as linking to a nonexistent page. All data is stored in plain text files with wiki formatting. Various plugins provide additional functionality, like a task list manager, an equation editor, a tray icon, and support for version control.
[[Licensing:|Licensing]] GNU General Public License [[(GPL)|GPL]] v2.0 (Source code)