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Embed Extension

This extension can embed rich content (like videos, tweets, etc.) from other websites.

The syntax is very simple - simply place any https:// URL on its own line like this:

Check out this video!

If the link points to embeddable content, it will be replaced with the rich HTML needed to embed it:

<p>Check out this video:</p>
<iframe width="200" height="113" src="" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


This extension is bundled with league/commonmark. This library can be installed via Composer:

composer require league/commonmark

You’ll also need to install a third-party OEmbed library - see the Adapter section below.


Configure your Environment as usual and add the EmbedExtension provided by this package:

use Embed\Embed;
use League\CommonMark\Environment\Environment;
use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
use League\CommonMark\Extension\Embed\EmbedExtension;
use League\CommonMark\MarkdownConverter;

// Define your configuration
$config = [
    'embed' => [
        'adapter' => new OscaroteroEmbedAdapter(), // See the "Adapter" documentation below
        'allowed_domains' => ['', '', ''],
        'fallback' => 'link',

// Configure the Environment with all whatever other extensions you want
$environment = new Environment($config);
$environment->addExtension(new CommonMarkCoreExtension());

// Add this extension
$environment->addExtension(new EmbedExtension());

// Instantiate the converter engine and start converting some Markdown!
$converter = new MarkdownConverter($environment);
echo $converter->convert('');


This extension supports the following configuration options under the embed configuration:

adapter option

Any instance of EmbedAdapterInterface - see the “Adapter” section below.

allowed_domains option

This option defines a list of hosts that you wish to allow embedding content from. For example, setting this to [''] would only allow videos from YouTube to be embedded. It’s extremely important that you only include websites you trust since they’ll be providing HTML that is directly embedded in your website.

Any subdomains of these domains will also be allowed. For example, [''] would allow embedding from or

As an additional safety measure, we recommend that you also use a Content Security Policy (CSP) to prevent unexpected content from being embedded.

By default, this option is an empty array ([]), which means that all domains are allowed.

fallback option

This options defines the behavior when a URL cannot be embedded, either because it’s not in the list of allowed_domains, or because the adapter could not find embeddable content for that URL.

There are two possible values for this option:


league/commonmark doesn’t know how to obtain the embeddable HTML for a given URL - this must be done by an external library.

embed/embed Adapter

We do provide an adapter for the popular embed/embed library. if you’d like to use that. We like this library because it supports fetching multiple URLs in parallel, which is ideal for performance, and it supports a wide range of embeddable content.

To use that library, you’ll need to composer install embed/embed and then pass new OscaroteroEmbedAdapter() as the adapter configuration option, as shown in the Usage section above.

Need to customize the maximum width/height of the embedded content? You can do that by instantiating the service provided by embed/embed, configuring it as needed, and passing that customized instance into the adapter:

use Embed\Embed;
use League\CommonMark\Extension\Embed\Bridge\OscaroteroEmbedAdapter;

// Configure the Embed library itself
$embedLibrary = new Embed();
    'oembed:query_parameters' => [
        'maxwidth' => 800,
        'maxheight' => 600,
    'twitch:parent' => '',
    'facebook:token' => '1234|5678',
    'instagram:token' => '1234|5678',
    'twitter:token' => 'asdf',

// Inject it into our adapter
$config = [
    'adapter' => new OscaroteroEmbedAdapter($embedLibrary),

// Instantiate your CommonMark environment and converter like usual
// ...

Custom Adapter

If you prefer to use a different library, you’ll need to implement our EmbedAdapterInterface yourself with whatever OEmbed library you choose.


If you need to wrap the HTML in a container tag, consider using the HtmlDecorator renderer:

$environment->addRenderer(Embed::class, new HtmlDecorator(new EmbedRenderer(), 'div', ['class' => 'embeded-content']));

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