$client_id = 'XXXXXXXXXXXXXXXXXXXXXXX'; // Id приложения
$client_secret = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'; // Пароль приложения
$redirect_uri = 'https://seolik.ru/social_login_callback/yandex.php'; // Callback URI

$url = 'https://oauth.yandex.ru/authorize';

$params = array(
    'response_type' => 'code',
    'client_id'     => $client_id,
    'display'       => 'popup'
);
	

header('Location: '. $url . '?' . urldecode(http_build_query($params)) ); exit()