The 1.1 version of AESTextCrypt for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free Mac app was originally developed by Chris Wood. AESTextCrypt for Mac lies within Security Tools, more precisely Personal Security.
From the developer:
AESTextCrypt is an easy-to-use open source tool for text encryption and decryption. Primarily intended for use with email, you can use it wherever you need to protect the text from prying eyes. The encrypted text can be copy/pasted into any text-handling application (e.g. email) instead of plain text. Convenience buttons are provided for clipboard operations.
You may want to check out more software for Mac, such as Key Holder or PasswordVault Lite, which might be similar to AESTextCrypt.