Grammarly - Clear, effective, mistake-free writing everywhere you type.
Write Together - Learn to write, together, one day at a time.
Wordtune - AI-powered writing companion
Kludd.co - Everyone writes.
Grammatica - AI powered writing assistant
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.