Zavala is a modern take on a traditional outliner. It supports all the things you want in a Mac app like multiple windows, keyboard shortcuts, a customizable toolbar, and a full menu bar.
Other features:
* OPML Import & Export
* Markdown Export
* iCloud syncing
* iCloud sharing with other iCloud users
* Tags for organizing Outlines
* Support for embedding images
* Print support
* Drag and drop
* Text formatting
* Links
* Completed items
* Notes
* Customizable fonts and sizes
* Backlinks
* Shortcuts Support
