Download of Zavala 3.3.6 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. This free Mac app was originally designed by Maurice Parker.
From the developer:
Zavala is a modern take on a traditional outliner. The application supports all the things you want in a Mac app like multiple windows, keyboard shortcuts, a customizable toolbar, and a full menu bar. It supports OPML import and export, Markdown export, iCloud syncing, and iCloud sharing with other iCloud users.