Workflowy - A better way to organize your mind.
Dynalist - Dynalist is a web app that lets you break down and organize your thoughts in the format of lists.
Orgzly - Outliner for notes, tasks and to-dos
Checkvist - A professional list-making tool. Minimalist, keyboard-centric online outliner and task management application. Free sharing, unlimited lists, cross-linking, free import and export. Markdown support. Created for geeks 🤓 and all keyboard lovers ⌨️
UV Outliner - UV Outliner is a small and powerful single-pane outliner.
OmniOutliner - OmniOutliner is a writing app for collecting information, outlining ideas, adding structure to any sort of writing.