I need to view the HTML generated by Drupal and it is pretty hard. If I want to the final output to be put through an HTML beautifier before sending it off to the client where would I do that?

I am sure some of the page optimization utilities on the admin/config/development/performance or the advagg module are at the right place in the pipeline. What stage or APIs would I have to hook into to accomplish something this?

Are there any APIs which can be hooked into to accomplish this or even modules to this?

1 Answer 1


Yes, in advagg is a good example, you have to get the response content with $response->getContent() in a response subscriber http://cgit.drupalcode.org/advagg/tree/src/EventSubscriber/ResponseSubscriber.php?h=8.x-3.x

  public function onResponse(FilterResponseEvent $event) {
    // Only care about HTML responses.
    if (stripos($event->getResponse()->headers->get('Content-Type'), 'text/html') === FALSE) {

    $response = $event->getResponse();
    $html_markup = $response->getContent();
    // modify html markup
  • What is the appropriate stage in Drupal 7?
    – vfclists
    Jul 4, 2017 at 7:18
  • I see you've added a new tag for D7, don't know anything about this, but you can try to look in the D7 code of advagg
    – 4uk4
    Jul 4, 2017 at 7:33

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