QOwnNotes

QOwnNotes is a free open source (GPL) plain-text notepad. The program has support for markdown, and includes a to-do list manager that works on FreeBSD, Linux, MacOS and Windows. It can optionally work together with the notes application of ownCloud or Nextcloud.

Features
QOwnNotes saves each note created by the user as a separate text document. These documents can be tagged, sorted, or searched for using the app. QOwnNotes allows for the exporting of notes as a PDF, HTML document, or as a markdown file. QOwnNotes allows users to encrypt or decrypt notes using AES-256 by default, but also allows for custom encryption.

The interface of QOwnNotes can be customized; the user can move and hide different menus. Users can create custom themes, changing the font, text size, and colors used in the text editor.

Reviews
Linux Magazine, Linux Format, Linux Voice and Web Upd8 reviewed QOwnNotes. There is a more elaborate list of reviews and articles about QOwnNotes.