Click Through Rate (CTR) is measured by (clicks / delivered) * 100% and represents how many notifications were clicked based on how many were delivered to the FCM/APNS servers who then send it to your subscribers. It does not count:

swiping away the notification
clicking "Dismiss"
clearing notifications

Best Practices

CTR for push notifications varies widely among different platforms (Android, iOS, Web), vertical (news, games, travel, ecommerce, etc), type of notification (message from a friend, promotion, informative update), country, etc. Not unlike email, the variance is so wide as to make averaging a bit muddy.

To help with maximizing clicks on push, we regularly publish blog posts and best practices on how to utilize OneSignal to get the maximum engagement from users.

A common best practice to increase CTR and user engagement is to send subscribers messages based on topics they are interested in. If your app publishes a wide range of topics and you send more than 1 notification a day, your users likely don't want to know about every push you send.

Websites can easily ask users what they would like notifications about using our Category Slidedown Prompt. This will allow you to group users by the different topics you offer so you can setup Segments and target users with the notifications they care about.

More actionable ideas:

Troubleshooting Low CTR

There are a couple reasons that CTR could be dropping, review the below questions for common issues and solutions:

Who are you targeting?

Over time, your users will get new devices. They will likely not unsubscribe from your app or website on the old device, but they may subscribe to your app or website on the new device. In this case, there will be 2 subscriptions for this user. You can clean up older subscriptions by Deleting Users.

Free Plan Limitations

Free plans can only target 10,000 Web Push subscribers. No limits on Mobile App subscribers. If you have more than 10,000 web push subscribers, you may be sending to older devices. You can Delete Users to target newer subscribers or upgrade to a paid plan.

Changed sending patterns

Have you or your team started sending more or less notifications since the drop?
Perhaps you started sending more API messages and less Marketing Messages.

Did you change any of the segments being targeted? For instance did you used to send notifications to all users, but around the date of the drop, you started sending to less users within the segments.

What metrics are you specifically tracking?

Is your reporting tracking clicks or ctr?

Clicks would be the actual click event where ctr could change based on how many devices are being sent to.
Are you tracking only specific types of messages?
For example are you only tracking marketing messages or transactional messages or are you tracking all messages?

What are you sending?

You could be suffering from boring notifications. Data shows adding flare to the notification gets more clicks. This can be emojis, images, icons, personalizations, localizations or just engaging words.

Some examples of this can be found in our blog and documentation:

When did you the drop start?

Its important to check what specific timeframes are you comparing.

What date did you start seeing a decrease in clicks?
What dates in the past are you comparing with?

How are you gathering analytics data?

What reporting tools are you reviewing and how is the data generated?

How many notifications are you sending?

If you are sending too many notifications, this can look spammy to users. How many is too many?
This can be different depending on the platform and type of notifications you are sending, but if you are blasting users with notifications every few hours with content they may not be interested in, that usually leads to low CTR.

Did anything change?

Below are examples of code changes that could affect your click metrics.

OneSignal not active on all pages or initialized

Websites should include OneSignal on all or most pages of the site for best performance.
Mobile Apps should initialize OneSignal in the specific ways discussed in our Mobile Quickstart guides.

Multiple Service Workers

Web Push Notifications require Service Workers to run on the browser so the user can receive push. Adding multiple Service Workers on a website (for example a service worker for PWA) can cause issues with push being received and CTR.

Please see our Guide on adding multiple Service Workers to your site

If you have already fixed this or removed the other service worker, then users will need to return to the site for our service worker to be added again.

Notification Service Extensions

For Mobile Push, if you setup the Android Notification Service Extension and are calling complete(null) and displaying your own notification with Android API then this will stop clicks.

complete(null) suppresses the SDK's notification so OneSignal can't know that you generated a notification and therefore can't count click events.

iOS Apple does not allow the remote notification to be suppressed like Android. So this can't be an issue for iOS.