StackEdit vs Zim

StackEdit works within your browser. You need internet access to connect to the website, but once it's loaded, the site does not require an internet connection - you will be able to edit and save files locally. Additionally, you can use Fluid to turn it into a native desktop application.

Supports standard Markdown and Markdown Extra.

It is very easy to toggle between the preview and the editing windows. The black makes it a very focused writing environment. Of course it's possible to change that if needed.

StackEdit works directly from the browser, there's no need to install additional software as long as you have a web browser installed on your computer.

The preview shows in a collapsible pane on the right hand side.

StackEdit allows pushing a document directly to a list of publishing or file storage platforms or any SSH server.

Can export to .txt, .html and .pdf.

Files can be synchronized through Dropbox and Drive.

Notes can contain links to other notes, allowing you to reference important information when needed. This way the user can connect and reference many different pages in the app, keeping things clean and structured, unlike Evernote, which makes this a good Evernote alternative.

If/when the app is no longer developed (or if the user simply decides to no longer use the application or view/edit it on a non-supported platform), this can still be done with any plain-text editor.

Zim will automatically create a folder structure that fits your page hierarchy and adds/removes files such as images to/from appropriate folders.

Zim supports HTML, LaTeX, Pandoc Markdown, and RST. This allows ones documents to be easily used in a wide selection of other apps.

Windows, Linux, and BSD are supported with their own clients. This is nice for those that use multiple operating systems but still want to use the same app on each.