UV Outliner Alternatives for Linux

Task Coach is a free and open-source personal task manager designed to handle compound tasks and notes. It's a versatile tool for organizing your to-do list with support for subtasks, categories, and tracking time spent on tasks, making it suitable for both simple task management and more complex project organization.

Ora is a comprehensive, real-time project management platform designed for teams of all sizes. It offers a flexible and intuitive interface, enabling teams to manage tasks, track time, collaborate effectively, and streamline workflows within a single workspace. From agile methodologies to traditional project planning, Ora provides the tools necessary to enhance productivity and achieve project goals.

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.

Todo.txt is a simple yet powerful command-line task management system. It leverages a plain text file to store your to-do list, making it highly portable, easily searchable, and compatible with numerous tools and operating systems. Its minimalism offers a clean separation from complex feature sets, focusing purely on task management.

Tasque is a free and open-source task management application designed for simplicity and efficiency. It helps users organize tasks, manage to-do lists, and optionally track time.

Conqu is a versatile task management application designed to help users organize their tasks, projects, and notes effectively. It offers a robust feature set including cloud sync, hierarchical task structures, integrations with popular services, and tools for both individual productivity and team collaboration.

GeeTeeDee is a powerful, yet lightweight and portable task management application designed to help users implement the 'Getting Things Done' methodology. It offers a unique blend of hierarchical organization, visual tools, and robust synchronization options, enabling efficient task tracking and productivity across various devices, even offline. Its focus on privacy and user control makes it a standout choice for personal and professional task management.

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.

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.

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.

SuperNotecard is a comprehensive writing tool designed to assist writers of fiction and nonfiction. It provides a dynamic environment for organizing notes, brainstorming ideas, managing characters, and structuring narratives through familiar paradigms like notecards and outlines, aiming to enhance productivity and creativity.

iRedMail is a comprehensive, free, and open-source mail server solution designed for ease of deployment and maintenance. It bundles popular components like Postfix, Dovecot, and Roundcube, providing robust email, calendar, and contact management capabilities.