Apps to Tree Structure

Gruik is a powerful, free, and open-source note-taking service designed for users who value privacy, organization, and control over their data. Offering robust features like hierarchical organization, offline access, rich text formatting, and synchronization options, it provides a flexible platform for managing notes, ideas, and personal knowledge wikis.

MyTetra is a versatile, cross-platform information manager designed for collecting, organizing, and managing various types of data. It excels as a portable note-taking application, personal information manager, and notebook, offering a robust outliner and rich text editing capabilities.

The Guide is a discontinued, portable desktop application designed for creating and organizing information in a hierarchical tree structure. It functions as an outliner and a basic personal information manager, allowing users to associate text and notes with each node in the tree.

SynWrite is a comprehensive and free source code editor for Windows, serving as an excellent Notepad replacement with robust features for various programming and web development tasks. It's designed for performance and extendibility, making it suitable for both novice and experienced developers.

Piggydb is an open-source web notebook application designed for building and managing knowledge bases, either individually or collaboratively. It emphasizes structured organization through hierarchical tagging and concept mapping.

ToDoList is a robust, free task management software designed for individuals and teams seeking a highly customizable, tree-structured approach to project organization. It excels in breaking down complex projects into manageable subtasks, offering features like Gantt charts, Kanban boards, and extensive export options without requiring a web connection.

wikidPad is a free and open-source wiki-like notebook application that allows you to store your thoughts, notes, and snippets of information in a highly organized and cross-referenced manner. Its strength lies in the effortless creation of links between pages, making it easy to navigate and connect related ideas.

Leanote is a versatile self-hosted note-taking application that blends rich text editing with Markdown support. It offers seamless synchronization across multiple devices and features built-in blog publishing capabilities, making it a powerful tool for both personal information management and content creation.