François-Régis Ferry

URL To Featured Image allows you to use an image hosted anywhere on the internet as the featured image (post thumbnail) for any post, page, or custom post type.
Perfect for: 
– Using CDN-hosted images as thumbnails. 
– Saving server space by not uploading large images. 
– Dynamically updating featured images from an external source.
Key Features: 
– Simple URL field in the post editor. 
– Works with posts, pages, and custom post types. 
– No extra database tables. 
– Fully compatible with WordPress themes and loops. 
– Uses standard WordPress functions like <code>the_post_thumbnail()</code>. 
– Ability to save the target image n the media libary if needed
How it works: 
When displaying the post, the plugin replaces the default WordPress featured image with the one provided via the URL.
<h3>Custom Hooks</h3>
<h4>Filters</h4>
<ul>
<li>
<code>friss_utfi_post_type_exclusions</code> 
Filters the post types where the URL To Featured Image metabox should not appear. 
Parameters:
<ul>
<li>(array) $exclusions_list List of post types where the metabox is excluded. </li>
<li>(object) $post Current post. 
Return: (array) Modified exclusions list.</li>
</ul>
</li>
<li>
<code>friss_utfi_url_allowed</code> 
Filters whether an external image URL is allowed before fetching. 
Parameters:
<ul>
<li>(bool) $authorization Whether the URL is allowed. </li>
<li>(string) $url The external image URL. </li>
<li>(array) $parts Parsed URL parts (from <code>wp_parse_url</code>). 
Return: (bool) True to allow, false to block.</li>
</ul>
</li>
<li>
<code>friss_utfi_allowed_mime_types</code> 
Filters the allowed MIME types for external images. 
Parameters:
<ul>
<li>(array) $mime_types Allowed MIME types. 
Return: (array) Modified list of MIME types.</li>
</ul>
</li>
<li>
<code>friss_utfi_max_image_size</code> 
Filters the maximum allowed image size when fetching external images. 
Parameters:
<ul>
<li>(int) $size Max file size in bytes. 
Return: (int) Modified maximum size.</li>
</ul>
</li>
<li>
<code>friss_utfi_image_data</code> 
Filters the raw image data fetched from the external URL. 
Parameters:
<ul>
<li>(string) $image_data Raw image data (string). </li>
<li>(int) $post_id Current post ID. 
Return: (string) Modified image data.</li>
</ul>
</li>
<li>
<code>friss_utfi_external_featured_image_alt</code> 
Filters the alt text for the external featured image. 
Parameters:
<ul>
<li>(string) $alt_text The alt text (default: post title). </li>
<li>(int) $post_id Current post ID. 
Return: (string) Modified alt text.</li>
</ul>
</li>
<li>
<code>friss_utfi_external_featured_image_styles</code> 
Filters the inline CSS styles applied to the external featured image. 
By default, the plugin enforces responsive behavior (<code>max-width:100%; height:auto;</code>). 
Parameters:
<ul>
<li>(string) $default_styles The default style string. </li>
<li>(int) $post_id Current post ID. 
Return: (string) Modified CSS styles.</li>
</ul>
</li>
</ul>

URL To Featured Image

Set any external image URL as your post's featured image automatically.

Archivarix

Archivarix External Images Importer will scan your posts and pages for external urls in src/srcset attribute for all img tags. Based on configured settings it can:
<ul>
<li>Download images from their external locations</li>
<li>Download images from Internet Archive (Wayback Machine)</li>
</ul>
You can choose what to do with images that could not be retrieved from external sources.
For further information and instructions please see <a href="https://archivarix.com/en/wordpress/" rel="nofollow ugc">Archivarix WP Plugin</a>

Archivarix External Images Importer

Works great!
I imported several posts into a site running WordPress 5.9.3 with Gutenberg and the Archivarix External Images Importer plugin imported the external images without any issues. I've tested a few other image importer plugins but none of them had the ability to scan a site and import from existing content like this one does.

Works with Gutenberg

Import external images in posts and pages from its original external sources or Web Archive if original source is unavailable.

URL To Featured Image vs Archivarix External Images Importer