I have been working on a plugin for the Atom editor as a side project. It allows you to connct to a WordPress site and pull and push posts and pages.
I created this plugin to make it a bit of a nicer experience for developers to create pages in HTML and for writers to write with markdown in an editor that is really good for markdown editing.
The little bit of a sticking point currently is the authentication method. Right now we are using basic auth, which is fine but not the best for security. The issue with that is that the user and pass is transmitted as plain text. However, if you are using SSL then it’s more ( not completely ) secure.
If you are using it to devolop a site locally, then there is no promblem. I always develop locally then push my changes to the remote site. I don’t directly edit the remote site. So right now, I recomend this workflow.
If you need to edit remotely, hang off for a more secure implimentation.
To see more about how it works, check it out here: https://github.com/Zackio/wpedit