Tree Notebook is a hierarchical notes manager designed for keeping personal information. The notebook consists of two parts: the public part can be accessed without password, the private part is encrypted, it requires entering a password in order to be opened and used. Tree Notebook has an iOS mobile counterpart (iPhone and iPad devices). The data can be synchronized between the Windows computer and up to three iOS devices via a local Wi-Fi network. No access to Internet is needed for synchronizing. Tree Notebook keeps a tree-like multilevel hierarchy of folders and notes. Any folder can include notes and other folders, and so fourth. Any item (a note or a folder) can include text of any size. Besides, items can keep attachments like images or other files. Tree Notebook has useful navigation tools: three separate panes for the entire tree, the current folder in the tree, the current item in the folder, status line indicating the current position in the tree, the lists of History and Favorites which alleviate getting back to the items recently or frequently visited. The app supports quick global search (simplified or conditional) and also local search inside an item text. The information in Tree Notebook can be attributed in many ways by using various font types, colored flags, graphic icons. The items can be sorted out by several criteria: alphabetically, by creation or modification time, and even by hand (in manually defined order). Among others, Tree Notebook includes a calendar feature. Any item can have an Event attribute and serve as an alarm clock or reminder. Tree Notebook can import data from OneNote and Evernote. It can also export the information to the Evernote and simple RTF formats. The Windows app is free without any limitations. The iOS app is free for up to 100 public items and 100 private items (200 items in total). To remove the limitation the user is kindly asked to make a one-time payment of $10 USD.