Elias Lackner

Upload Directory Cleaner scans through your WordPress upload directory searching for all files not being registered in your Media Library. After the scan, choose which files to delete from the list showing all unregistered files.
Features:
<ul>
<li>Archive Directory</li>
<li>Scan Directory (Settings: Exclude top-level directories and files from the scan or add custom ignore strings.)</li>
<li>Delete Files (Settings: Keep Thumbnails, Delete Empty Directories)</li>
</ul>

Upload Directory Cleaner

The UDC plugin allows you to scan and delete all unregistered files from your Wordpress upload directory.

Arnoud Klaren

Only for registered ScanCircle partners. See the <a href="https://www.scancircle.com/scancircle/partner-program" rel="nofollow ugc">ScanCircle partner program</a>.
Login to your ScanCircle partner page and select the Scan Widget tab to generate the required ScanCircle shortcode and copy/paste it into your post.

ScanCircle

Shortcode handler for the scan widget on ScanCircle partner websites.

Upload Directory Cleaner vs ScanCircle