Snipt - Code snippets for teams.
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.
Quiver - Quiver is a notebook built for programmers.
Boostnote - Boostnote is an open-source note-taking app.
GitHub Gist - Gist is a simple way to share snippets and pastes with others.
Standard Notes - A safe place for your notes, thoughts, and life's work