is_ssl

The timeline below displays how wordpress function is_ssl has changed across different WordPress versions. If a version is not listed, refer to the next available version below.

WordPress Version: 6.3

/**
 * Determines if SSL is used.
 *
 * @since 2.6.0
 * @since 4.6.0 Moved from functions.php to load.php.
 *
 * @return bool True if SSL, otherwise false.
 */
function is_ssl()
{
    if (isset($_SERVER['HTTPS'])) {
        if ('on' === strtolower($_SERVER['HTTPS'])) {
            return true;
        }
        if ('1' === (string) $_SERVER['HTTPS']) {
            return true;
        }
    } elseif (isset($_SERVER['SERVER_PORT']) && '443' === (string) $_SERVER['SERVER_PORT']) {
        return true;
    }
    return false;
}

WordPress Version: 5.5

/**
 * Determines if SSL is used.
 *
 * @since 2.6.0
 * @since 4.6.0 Moved from functions.php to load.php.
 *
 * @return bool True if SSL, otherwise false.
 */
function is_ssl()
{
    if (isset($_SERVER['HTTPS'])) {
        if ('on' === strtolower($_SERVER['HTTPS'])) {
            return true;
        }
        if ('1' == $_SERVER['HTTPS']) {
            return true;
        }
    } elseif (isset($_SERVER['SERVER_PORT']) && '443' == $_SERVER['SERVER_PORT']) {
        return true;
    }
    return false;
}

WordPress Version: 4.6

/**
 * Determines if SSL is used.
 *
 * @since 2.6.0
 * @since 4.6.0 Moved from functions.php to load.php.
 *
 * @return bool True if SSL, otherwise false.
 */
function is_ssl()
{
    if (isset($_SERVER['HTTPS'])) {
        if ('on' == strtolower($_SERVER['HTTPS'])) {
            return true;
        }
        if ('1' == $_SERVER['HTTPS']) {
            return true;
        }
    } elseif (isset($_SERVER['SERVER_PORT']) && '443' == $_SERVER['SERVER_PORT']) {
        return true;
    }
    return false;
}

WordPress Version: 3.7

/**
 * Determine if SSL is used.
 *
 * @since 2.6.0
 *
 * @return bool True if SSL, false if not used.
 */
function is_ssl()
{
    if (isset($_SERVER['HTTPS'])) {
        if ('on' == strtolower($_SERVER['HTTPS'])) {
            return true;
        }
        if ('1' == $_SERVER['HTTPS']) {
            return true;
        }
    } elseif (isset($_SERVER['SERVER_PORT']) && '443' == $_SERVER['SERVER_PORT']) {
        return true;
    }
    return false;
}