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 in 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>(object) $post Current post object. 
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_post_thumbnail_html_preserve_existing_markup</code> 
Controls whether the existing markup is preserved before regenerating the HTML via the post_thumbnail_html filter hook. 
Parameters:
<ul>
<li>(bool) $preserve_existing_markup Whether to preserve or not the existing image tag markup. </li>
<li>(int) $post_id Current post ID. 
Return: (bool) True to preserve, false to skip this step.</li>
</ul>
</li>
<li>
<code>friss_utfi_post_thumbnail_html_attributes</code> 
Filters the image tag attributes for the recreated html content generated by the post_thumbnail_html filter hook. 
Parameters:
<ul>
<li>(array) $attributes The attributes array to filter. </li>
<li>(int) $post_id Current post ID. 
Return: (array) Modified attributes array.</li>
</ul>
</li>
<li>
<code>friss_utfi_allowed_img_attributes</code> 
Filters the whitelist of allowed attributes kept on the generated tag when rendering the external featured image. 
Parameters:
<ul>
<li>(array) $allowed_attributes List of allowed attribute names (default: src, alt, width, height, class, loading, decoding).</li>
<li>(int) $post_id Current post ID. 
Return: (array) Modified list of attribute names.</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>
<li>
<code>friss_utfi_active_post_types</code> 
Filters the final list of active post types for which the URL To Featured Image feature is enabled. 
Parameters:
<ul>
<li>(array) $active_post_types Current list of active post type slugs. 
Return: (array) Modified list.</li>
</ul>
</li>
<li>
<code>friss_utfi_active_post_types_posttype_exclusions</code> 
Filters the list of post types excluded before computing active post types. 
Parameters:
<ul>
<li>(array) $exclusions Current exclusions (internal post types or ones you want suppressed). 
Return: (array) Modified exclusions list.</li>
</ul>
</li>
</ul>

URL To Featured Image

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

Dan Griffiths

Adds a robust third-party product system to Easy Digital Downloads. When activated, adds new fields to the Download Prices meta box allowing you to specify redirect details.
External Products is based on the extension of the same name by WebDevStudios.

Easy Digital Downloads – External Products

Was looking for exactly this: an option to add third party plugins on my own EDD shop. 

Perfect

Adds a robust third-party product system to Easy Digital Downloads

URL To Featured Image vs Easy Digital Downloads – External Products