Push notifications is a very special ad format, and there's a reason why it has become extremely popular in the last years. We link it to the fact that advertisers manage to get a high conversion rate with this ad format in many categories. It's a pleasure to announce that we support this ad format and here we will explain how push notifications work. So we hope this article helps you to decide whether it fits your needs and purposes.

How to set up push notifications

Push notifications are not like the most ad formats by their design. They are initiated by an ad server, not users. Thus, visitor action is only required in the very beginning when they agree to a subscription request. After that, the ad server starts delivering ads periodically (every 3 hours by default; we can change the timing upon request).

Like with other ad formats, targeting is available with Push Notifications. In this case, targeting works at the moment a visitor subscribes to receive notifications.

Please note that Push Notifications can be considered aggressive by your website visitors. Make sure you don't annoy them by frequent and boring ads. Otherwise, it may result in cancelled subscriptions.

Therefore, it is vital to set impressions capping for your campaigns:

push notifications - adserver.online

and a push zone:

push notifications - adserver.online

Additional limitations of push notifications:

  • websites require an HTTPS certificate in order to start using this ad format
  • it doesn't work with Safari browser due to technical limitations

Demo here https://adserver.online/demo/push

Related components

1. Subscriptions tab in the Reports menu.

A new subscription appears on a list every time a website visitor clicks 'Allow' button on a subscription request in a browser.

2. Zone format on a zone form:

The invocation code contains two parts, so we urge you to read a description on a zone view page carefully.

3. Ad format on a 'Create ads' form (Step #1):

Code configuration

Push JS-code supports the following options:

  • loadsBeforeFire – how many pages should be opened before the browser will ask for subscription
  • timeout – timeout in seconds before the browser will ask for a subscription after the visitor opened page

Configuration example:

<script data-cfasync="false">
(function(w,a){w[a]=w[a]||{};w[a].queue=w[a].queue||[];w[a].queue.push(function () { 
   _ASO.PushOptions = { 
     loadsBeforeFire: 2,
     timeout: 5   


The push notifications subscription pop-up doesn't show up in Chrome / Firefox / Edge / Opera


  • In order to use Push Notifications, your website must use an HTTPS protocol
  • Ensure that you haven't blocked notifications. Click on the lock next to the address bar and ensure that you have Notifications: ask (or Notifications: allow)
  • Open the console from the browser developer tools and make sure there are no errors
  • Disable any ad blocker that may be blocking requests to an ad server
  • Make sure that the service worker is served from the root of your website (e.g. https://example.com/aso-worker.js), otherwise, it may not become active on some pages causing the starvation of method calls

The push notifications subscription pop-up doesn't show up in Safari

Adserver.Online doesn't support push notifications in Safari browser at the moment.

The push notifications subscription pop-up doesn't show up on iPhone / iPad

iOS and iPadOS doesn't support Web Push notification standard.

You get a Javascript error about the applicationServerKey


  • You cannot subscribe to the notifications, even when you have granted permission.
  • When you try to subscribe the user to push notifications, you can see this message in the browser developer console: DOMException: Registration failed - A subscription with a different applicationServerKey (or gcm_sender_id) already exists; to change the applicationServerKey, unsubscribe then resubscribe.


  • You get this exception because you are using multiple different ad network codes on the same domain. You should not do that! You can use only one ad network code per domain.
  • Make sure that you are using only one Adserver.Online ad code on your domain.
  • In any case, this exception can be fixed easily by resetting the browser subscription: go to browser preferences (or click the green lock near the address bar) and block the notifications for your domain, then allow notifications again and refresh the page.

Why some web push notifications are not delivered to the browser/device despite they were sent out by an ad server?

Please note, the ad server sends a notification to the browser's push service provided by Google, Mozilla, and Microsoft, but not to the end-user browser/device directly. Therefore, 3rd-party services are responsible for delivering a notification to the end-user browser/device.

The notification may not reach the end-user for various reasons:

  • the recipient device is turned off
  • the recipient device has no internet connection
  • the recipient device has airplane mode enabled
  • the recipient device has power-saving mode enabled
  • the browser is closed (some browsers, mainly desktop browsers, need to be open in order to receive push notifications)
  • the browser process that responsible for downloading the notifications runs in the background and may be killed for power saving; this happens mainly on mobile devices
  • the browser does not have the right permissions to download data from the internet when the screen is locked (in this case the notification may be lost)
  • the user has unsubscribed via browser preferences, but the browser push service wasn’t notified about that and considers the subscription valid
  • the user doesn’t use a given browser or device anymore (the browser push service should remove that subscription after several months of inactivity)
  • the browser receives the signal, but the internet connection is lost when it tries to download the notifications

This concludes our article about push notifications, their characteristic features, and limitations. No doubt, it is an interesting ad format that can be extremely profitable for both publishers and advertisers. Provided that everyone uses it, not abuses.