Buho is a note-taking application that lets you write the computer equivalent of sticky notes.
QOwnNotes
Free open source plain-text file markdown note taking with Nextcloud / ownCloud integration
កំណត់ចំណាំ
The notes plugin provides you a quick way to paste text, to write down a list of things, to leave a note to your friend, or whatever you had do with Post-It’s.