QOwnNotes - QOwnNotes is a free plain-text notepad with markdown support for Linux, Mac OS X and Windows, that works together with ownCloud Notes.
GNUPGK - A GnuPG Frontend GUI made in C#.
EncryptPad - EncryptPad is an application for viewing and editing symmetrically encrypted text.
TheLetterEncrypter - TheLetterEncrypter is a small (14KB download) AES-based text-encryption program.
Notepads - Notepads is a modern, simple yet powerful text editor for Windows 10
CTI Text Encryption - CTI Text Encryption is an encryption tool that can encrypt any text from messages and articles to codes, etc.