It supports [RSS](http://cyber.harvard.edu/rss/rss.html), [Atom](https://tools.ietf.org/html/rfc4287), [JSON Feed](https://jsonfeed.org/), and [RSS-in-JSON](https://github.com/scripting/Scripting-News/blob/master/rss-in-json/README.md) formats.
It’s barely usable at this point. Barely. Probably not even. A whole bunch of things haven’t been done yet. (See the [bug tracker](https://github.com/brentsimmons/Evergreen/milestone/1)).