ActivityPub: Show links behind text

Published: April 23, 2026 by Matze – Leave a comment

When linking a word in WordPress and publishing it in the Fediverse via ActivityPub, those links are getting removed. But what if you want to keep the links?

When asked about this in a feature request at GitHub, @obenland came up with a pretty nice solution I want to share here, which does exactly what I wanted.

In the end, the following text in WordPress:

The quick brown fox jumps over the lazy dog

Becomes this in the Fediverse:

The quick brown fox (https://en.wikipedia.org/wiki/Fox) jumps over the lazy dog

I just needed to adjust the filter, since I’m using only the excerpt when sharing my post content in Settings > ActivityPub > Settings > Activities > Post content via [ap_excerpt] (in a legacy template system). Thus, I cannot use the suggested filter activitypub_the_content as in the original. I need to use the generic post_content and check manually whether the current request is an ActivityPub request.

This is the final code:

<?php
/**
 * Transform links behind text to text (link).
 *
 * @see		https://github.com/Automattic/wordpress-activitypub/issues/1859#issuecomment-3480894020
 *
 * @param	string	$content Current content
 * @return	string Updated content
 */
function plugin_format_activitypub_links_with_urls( string $content ): string {
	if ( ! \function_exists( 'Activitypub\is_activitypub_request' ) || ! \Activitypub\is_activitypub_request() ) {
		return $content;
	}

	$content = \preg_replace_callback(
		'/<a\s+([^>]*?)href=["\']([^"\']+)["\']([^>]*?)>(.*?)<\/a>/is',
		function( $matches ) {
			$href = $matches[2];
			$link_text = \wp_strip_all_tags( $matches[4] );

			if ( empty( $href ) || \strpos( $href, '#' ) === 0 ) {
				return $matches[0];
			}

			if ( $link_text === $href ) {
				return $matches[0];
			}

			return $link_text . ' (' . \esc_url( $href ) . ')';
		},
		$content
	);

	return $content;
}

\add_filter( 'post_content', 'plugin_format_activitypub_links_with_urls' );
Code language: PHP (php)

This does only affect content that is viewed by a Fediverse client, though. It does not alter the content when embedding a post in another post on another page or similar.