Colon in YOURLS short URL

README.md

Why is the colon so special? Read here: https://planetozh.com/blog/2026/06/allowing-weird-characters-in-yourls-short-urls/

plugin.php

<?php
/**
 * Plugin Name: Allow Colon in Short URLs
 * Plugin URI: https://ozh.in/10i
 * Description: Allow the colon ":" in short URLs (like <tt>http://sho.rt/foo:bar</tt>)
 * Version: 1.0
 * Author: Ozh
 * Author URI: http://ozh.org/
 */

// No direct call
if( !defined( 'YOURLS_ABSPATH' ) ) die();

// Add the colon to the allowed short URL character set...
yourls_add_filter( 'get_shorturl_charset', 'ozh_colon_in_charset' );
function ozh_colon_in_charset( $charset ) {
    return $charset . ':';
}

// ...unless we are crafting a random keyword, to keep auto-generated keywords colon-free
yourls_add_action( 'add_new_link_create_keyword', function() {
    yourls_remove_filter( 'get_shorturl_charset', 'ozh_colon_in_charset' );
} );

// Don't let a keyword that contains a colon be mistaken for a URI scheme
yourls_add_filter( 'get_protocol', 'ozh_colon_get_protocol', 10, 2 );
function ozh_colon_get_protocol( $protocol, $url ) {
    // Nothing was detected as a protocol: leave as is
    if ( $protocol === '' ) {
        return $protocol;
    }

    // A genuine "scheme://..." URL (eg a bookmarklet target): leave as is
    if ( str_contains( $protocol, '/' ) ) {
        return $protocol;
    }

    // Here $protocol is a bare "scheme:" with no slashes. If the whole candidate
    // string consists only of valid short URL charset characters, it's one of our
    // keywords (eg "foo:bar"), not a URL: don't treat the colon as a scheme.
    $pattern = yourls_make_regexp_pattern( yourls_get_shorturl_charset() );
    if ( ! preg_match( '@[^' . $pattern . ']@', $url ) ) {
        return '';
    }

    return $protocol;
}