Coastline - Simple minimalist text editor. Create, open, edit and save plain text files.
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.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
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.
TextDrop - TextDrop is the fastest way to edit text files in your Dropbox using a web browser.
Standard Notes - A safe place for your notes, thoughts, and life's work