Code snippets to hide/manage routes in WordPress REST API

only-for-admins.php

<?php

add_filter( 'rest_authentication_errors', function( $result ) {
  if ( ! empty( $result ) ) {
    return $result;
  }
  if ( ! is_user_logged_in() ) {
    return new WP_Error( 'rest_not_logged_in', 'You are not currently logged in.', array( 'status' => 401 ) );
  }
  if ( ! current_user_can( 'administrator' ) ) {
    return new WP_Error( 'rest_not_admin', 'You are not an administrator.', array( 'status' => 401 ) );
  }
  return $result;
});

only-for-logged-in-users.php

<?php

add_filter( 'rest_authentication_errors', function( $result ) {
  if ( ! empty( $result ) ) {
    return $result;
  }
  if ( ! is_user_logged_in() ) {
    return new WP_Error( 'rest_not_logged_in', 'You are not currently logged in.', array( 'status' => 401 ) );
  }
  return $result;
});