Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
GitJournal - Manage your Notes from any Git Repo.
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.
Category Tabs for Google Keep - Better organize your Google Keep Notes
Standard Notes - A safe place for your notes, thoughts, and life's work
Calendar Note by Enex - Calendar Note app allows users to view the calendar so they can write notes and memos according to dates to get alerts about tasks.