A hierarchical note taking application, featuring rich text and syntax highlighting, storing data in a single xml or sqlite file.

Workflowy lets you organise your brain into easily manageable lists. It also works as a single-pane outliner with inline notes. It offers one-click hoisting (zooming into branches). The online version syncs with mobile apps.

Dynalist is a web app that lets you break down and organize your thoughts in the format of lists.

Manuskript is an open-source tool for writers, with outliner, character management, plot development, distraction-free editor, etc.

Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system.

Working on a project, researching a topic or writing an article? Walling makes it easy to break down your ideas, refine them and visually organize them.

wikidPad is a Wiki-like notebook for storing your thoughts, ideas, todo lists, contacts, or anything else you can think of to write down. What makes wikidPad different from other notepad applications is the ease with which you can cross-link your information.

Outliner for taking notes and managing to-do lists.

Memento is a personal database that allows you to store all personal data in one place.

The powerful, full-featured Personal Information Manager for Windows offering Email, Synchronization, Portability, Network support, Android and iOS versions.

Widget Board is a productivity tool that lets you create custom boards with your favorite widgets such as tasks, notes, media, date & time, weather, calendar and so much more!.

OmniOutliner is a start-to-finish writing app. Perfect for collecting information, outlining Big Ideas, adding structure to any sort of writing, and much more. From grocery lists to email drafts to long-form composition.