DocBook - DocBook is a schema (available in several languages including RELAX NG, SGML and XML DTDs, and W3C...
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Groff - The groff (GNU troff) software is a typesetting package which reads plain text mixed with...
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
pandoc - Pandoc is a Haskell library for converting from one markup format to another, and a command-line...
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.