Top Alternatives to OmniOutliner

WorkFlowy is a powerful yet simple organizational tool that leverages an infinite nested list structure. It helps users capture, organize, and manage ideas, notes, tasks, and projects through outlining and collaboration, making complex information digestible and actionable.

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.

CherryTree is a powerful, free, and open-source hierarchical note-taking application. It allows you to organize your thoughts, ideas, notes, and code snippets in a tree-like structure with rich text editing and syntax highlighting.

NixNote is an open-source, cross-platform desktop client for Evernote, offering a familiar interface and offline access to your notes.

MyLifeOrganized (MLO) is a highly customizable and powerful task management software designed to help individuals achieve their goals through intelligent organization and priority management.

KeepNote is a versatile note-taking application designed for organizing information in a hierarchical structure. Available on Windows, Linux, and macOS X, it features robust organization tools, including a tree-like outline, wiki-like linking, and support for embedded files and images. Although discontinued, its local storage and rich features make it a compelling tool for detailed note-taking and research.

EssentialPIM is a versatile personal information manager designed to help you organize your life. It allows you to manage appointments, tasks, notes, contacts, passwords, and more, all within a single, customizable application available for desktop and mobile platforms.

Org-mode is a powerful and flexible mode for GNU Emacs, designed for note-taking, project planning, to-do list management, and authoring documents. It utilizes simple plain text files with intuitive markup.

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.

Checkvist is a versatile online outlining and task management tool designed for individuals and teams. It excels at organizing information hierarchically, making it ideal for project planning, managing tasks, and creating detailed checklists. Its keyboard-centric approach and robust features streamline workflow and enhance productivity.

UV Outliner is a discontinued, single-pane outliner known for its hierarchical structure and multicolumn support. It aimed to provide a flexible platform for note-taking, task management, novel writing, and brainstorming through a clean design and various integration options.

Moo.do is a collaborative task management and outlining tool designed to consolidate your work, notes, and tasks into a single, flexible interface.

Dynalist is an outliner and productivity tool designed to help users organize ideas, tasks, and information in highly structured, hierarchical lists. It leverages the power of outlining to break down complex subjects into manageable parts, facilitating everything from simple task management to large-scale project planning and knowledge organization.

MemPad is a highly portable and lightweight note-taking application designed for hierarchical organization of information. It offers a tree-like structure, enabling users to manage vast amounts of data efficiently. With features like strong encryption and offline capabilities, MemPad serves as an excellent tool for secure and private information management on the go.

Germ.io is a collaborative idea management and project planning tool that helps teams capture, refine, and transform initial concepts into structured and actionable project plans.

Manuskript is a free and open-source writing software designed specifically for authors. It provides a structured environment to plan, outline, and write novels and other complex documents, featuring tools for character tracking, plot management, and a distraction-free interface.

Quoll Writer is a dedicated writing application designed to provide a focused and organized environment for authors, particularly those working on long-form projects like novels. It combines distraction-free writing tools with robust project management features, allowing writers to concentrate on their narrative while keeping track of characters, plot points, and research materials.

Goalton.com is a comprehensive platform designed for effective goal setting, task management, and project execution. It provides a flexible and hierarchical structure to organize your work, combining various views like Kanban boards, mind maps, and outlines to suit different workflows and collaboration needs for individuals and teams.

Notion is an all-in-one workspace that combines notes, documents, wikis, project management, and databases into a single, highly flexible platform. It empowers teams and individuals to manage knowledge, plan projects, track tasks, and collaborate seamlessly, adapting to nearly any workflow or organizational structure.