Vincent Robic

This plugin updates all URLs in the database after moving your site from one domain to another. It is useful for switching between development, testing and production stages.
Why this plugin ? WordPress stores absolute URLs in :
<ul>
<li>posts (including pages and custom post types), drafts</li>
<li>excerpts</li>
<li>medias</li>
<li>custom fields</li>
<li>options (including ‘siteurl’ and ‘home’, in wp_options table)</li>
<li>GUIDs (only for development)</li>
</ul>
When moving your website to a new domain, all these links will point to your old domain name and become outdated.
<h3>Prerequisite</h3>
Before moving the website, consider making a backup of the database. Then, once the site has been moved, you will need to manually update ‘siteurl’ in the ‘wp_options’ table, in order to access the WordPress Administration panel. 
For further information, see https://codex.wordpress.org/Changing_The_Site_URL

UmanIT Update URLs

Updates all URLs in the database after moving your site from one domain to another.

Nerd Warehouse

Allow users to check domain name availability directly from your website. Availability is shown without redirecting users. With the use of widgets you can add the domain search to multiple locations on your website. You can also quickly check domain availability yourself using the admin dashboard widget. This plugin is multisite compatible and free.
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WordPress Domain Search

This plugin allows you to create domain search widgets and check domain availability from the admin dashboard.

UmanIT Update URLs vs WordPress Domain Search