Siteimprove

The Siteimprove CMS Plugin bridges the gap between the WordPress content management system (CMS) and the Siteimprove Intelligence Platform. Now you can scan your website for errors as soon as a page is published, allowing you to fix mistakes, optimize content, and manage your site more efficiently. 
The plugin also provides you access to Prepublish, an add-on which allows you to check your page for issues before it has been published.

Turn your most complex website challenges into manageable tasks—all from a single platform

editz

Allow your readers to become citizen editors. Editz is a free service that allows your readers to post spelling, grammar, factual, and other errors straight to you. After you or any other wordpress admin approves the edit, the Editz plugin will automatically fix the error. It’s like magic.
You can learn a bit more about it by watching this video: http://www.youtube.com/watch?v=858FDGwIp2g

Editz

Editz allows your readers to become citizen editors.

Siteimprove vs Editz