Michael Thomas

404 errors are generally very ‘expensive’ on WP sites as they cause WP to run on every attempt, slowing 
down your site and causing additional load on your web hosting environment.
WP Speed 404 can either suppress or log and email any 404 errors affecting your site under wp-content, wp-admin and 
wp-includes (configurable).

WP Speed 404

WP Speed 404 can either suppress or log any 404 errors affecting your site under wp-content, wp-admin and wp-includes (configurable).

Yoast

Remkus de Vries

Redirectioner allows WordPress admins to have control over their dead links and redirects from inside the admin panel. <a href="https://redirectioner.com" rel="nofollow ugc">Redirectioner</a> records all URLs that users have visited and allows the admin to easily create 301 and 302 redirects to valid pages on their site. Redirects can also be created based on the best possible match for the URL the visitor was most likely trying to reach.
<blockquote>
Support & Bug Reports 
 If you’re in need of support or would like to file a bug report, please head over to our Github repository and <a href="https://github.com/thememix/redirectioner/issues" rel="nofollow ugc">create a new issue.</a>
</blockquote>
<h4>Features:</h4>
<ul>
<li>Get list of 404 URLs as they happen inside the admin panel</li>
<li>Easily redirect 404 URLs to existing pages or choose to ignore the 404 error</li>
<li>Provides the ability to automatically create redirects based on the URL the visitor was most likely trying to visit</li>
<li>Provide visitors with a list of suggested pages on the 404 page when a automatic redirect can not be made</li>
<li>Ability to suggest tag and category pages</li>
<li>Ability to create automatic redirect for misspelled tag and category pages</li>
<li>Ability to view logs of hits to 404 pages and redirects including referrer data</li>
<li>Ability to remove automatically remove redirects when the URL matches a new page or post permalink</li>
<li>Ability to automatically remove manual and automatic redirects once they are no longer being used</li>
<li>All features work with both pages and posts</li>
<li>Create automatic redirects for any URL resolving to a single page or post that isn’t the current permalink</li>
<li>Basic stats of plugin usage</li>
</ul>
Convert your 404 traffic by providing your site visitors with a better browsing experience and eliminate 404 URLs on your site.

Redirectioner

Creates automatic redirects for 404 traffic and page suggestions when matches are not found providing better service to your web visitors.

WP Speed 404 vs Redirectioner