SdeWijs

This Zoomify plugin for WordPress allows you to upload .zif files to your media directory. You can then create the Zoomify imagebox 
with toolbar by using the shortcode <code>[zoomify file="fileUrl" zskinpath="Default/Dark/Light" zoomlevel=100]</code> (zoomlevel is optional), where “fileUrl” is the url/permalink to the zif-file. 
The skin parameter has three options: Default, Dark and Light. If the skin parameter is omitted in the shortcode the Default skin will be used.
For example, if the permalink to your file is http://example.com/wp-content/uploads/2016/10/myAwesomemap.zif, the shortcode will look like this
<pre><code>[zoomify file="http://example.com/wp-content/uploads/2016/10/myAwesomemap.zif" zskinpath="Default"]
</code></pre>
If copy-pasting this example does not work, please type out the shortcode manually in your WP editor so the double quotes are properly formatted.
I am not connected to Zoomify in any way, I coded this plugin for personal use and figured this may come in handy for other Zoomify users.
Each Zoomify image had it’s own unique identifier, so you can add muiltiple Zoomify images to a page.

Zoomify embed for WP

This plugin offers an easy way to embed zoomify .zif files in your WordPress website.

terrazoom

Make any image zoomable no matter how large. The ZoomifyWP Free plugin for WordPress offers an easy way to embed Zoomify files into your WordPress site. To use you must upload the folder created by the Zoomify converter to your wp-content/uploads/zooms directory via FTP. If the zooms directory does not exist, you must add it. You can then embed a shortcode [zoomify filename=”myCoolZoom”] to your post or page.
Zoomify Free includes everything you need to create amazing and interactive zooms of images with a simple three-step zoom process. Download the version for your platform at http://www.zoomify.com/free.htm

ZoomifyWP Free

The ZoomifyWP Free plugin for WordPress offers an easy way to embed Zoomify into your WordPress site.

Zoomify embed for WP vs ZoomifyWP Free