Getting Started With Web Push Notifications

A Definitive Guide To Understand How Browser Notifications Work

What are Web Push Notifications?

Web push notifications are clickable rich content messages sent to your device by a website or a web app. Push notifications are delivered to your mobile device or desktop, even when your browser is closed.
These notifications can only be sent to users who have subscribed to these notifications from a specific website on Chrome, Firefox and Safari.

As these notifications are pushed to user’s device, users don’t have to be present on the specific website to receive these notifications.
Push Notifications are best used for delivering time bound content to engage users. Some of the popular use cases include retargeting users abandoning the cart, activating dormant users with offers, retaining loyal readers with personalized content and more.
1.1 What are web push notifications used for?
Just like native app notifications, browser notifications are meant to facilitate timely flow of information. Though users are not expected to download and install an application. Users can simply subscribe to these notifications by clicking on the Allow button on the permission prompt.
Web push notifications are used by app developers to build user engagement and retention. Businesses across categories are increasingly relying on web push notifications as a communication channel. SMBs are relying heavily on web push notifications as a communication channel to generate traffic consistently.The primary reason for this adoption is plummeting response to email, SMS and display ads.
Some of the popular use cases are:
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1.3 Where do these notifications appear on desktop and mobile
Web push notifications are delivered even when the user is not on the website. On Desktop, these notifications are delivered to the browser, right next to the taskbar.
The user must be an active subscriber to receive these notifications. It is important to note that Apple is yet to support web push notifications on iOS. Follow this thread on the status of push notifications and service workers on iOS.

How do Web Push notifications work?

Once you've enabled web push notifications on your website, your web visitors will start seeing a subscription prompt. You will be able to send notifications to these users after they have subscribed to your website notifications.

2.1 Anatomy of a Web Push Notification Message

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There are 4 key elements that constitute a push notification - Title, Description, Landing Page URL, Icon and Banner Image and Call To Action Buttons. It is important to understand features of Web Push Notifications like Banner Image and Call To Action Buttons are only available for Chrome. Here is a breakdown of how each of these elements-
Title - Every notification needs an eye-catching title. The catchier the title, higher are the chances that your subscribers will click on it.
Description - A description is a short message that supports your title and offering. Write all that needs to be conveyed but squeeze it in the form of a short message making sure you don’t compromise with its effectiveness. You can even add emojis to your notification's title and description. It is important to note that there is no definite character limit for Notification Title or Description. Depending upon the device, Desktop or Mobile characters get trimmed. Both the title and description can be deep linked to a specific URL.
Website Domain - The website domain which has sent the notification.
Call to Action Buttons - You can add up to 2 CTA Buttons in a notification. CTA Buttons can be only added to Chrome notifications. Firefox and Safari are yet to extend support to this. These buttons can be used to trigger different actions – for eg taking the user to a landing page, sending out a social message (Tweet), triggering the Play Store or the Dialer.
Icon - You can add an icon to your notification to build a better recall. The default icon is bell icon. Users are nowadays bombarded with notifications, hence it becomes essential to let your users know when your push notification pops up. Adding your logo helps users in building a brand recall. The recommended icon should be 100*100px and should be less than 20kb in size.
Banner Image - Banner size images were introduced recently with Chrome 56. This was one of the most awaited features and rightly so - Visuals help in impactful communication and can help you amplify your message by as much 189%. As much as your notification title and the message should be eye catchy, adding a bright banner image related to your notification content will simply just increase your chance of getting that click.
Recommended Dimension : 360*240px. Size of the banner image should be less than 240kb or less.
2.2 How do they work?
There are three actors involved with delivering a push notification, along with a fourth, optional, component for advanced functionality.
  1. Push Notification Service: Each browser, including Chrome, Safari and Firefox have their own notification delivery service. Chrome uses Google Cloud Messaging ( and now Firebase Cloud Messaging ), Safari uses Apple Push Notification Service ( APNS ) and Firefox uses
  2. Service Worker Registration: Developer must register the service worker on the browser. This is only for Chrome and Firefox. Safari does not support service workers.
  3. User’s Subscription ID: Subscriber ID is generated when a user opts in to receive notifications from a specific website.
Additionally an SDK (OS client library Software Development Kit) can be added to a web app for extended segmentation and analytics capabilities.
2.3 Adding to a Website / Web App
  1. Website owners can start by implementing service workers for Chrome and Firefox browsers, and by generating APN certificate for Safari browsers.
  2. Browsers provide standard API calls to read user subscription permissions for the domain and to prompt visitors for notification consents.
  3. Website owners can additionally use service providers like iZooto and use their SDK to take care of the first two steps.
  4. Website owners can push notifications to their subscribers by executing APIs provided by browser push system. This can also be done through UI.
2.4 User Subscription and Activation
  1. Users are prompted for notification subscription whenever they visit the website with a default browser prompt. Developers and website owners can chose to trigger subscription prompts conditionally.
  2. A unique registration key is generated by browser for every user who subscribes to notification.
  3. Notification service provider stores the keys at their end along with any additional data points to identify subscribers uniquely.
2.5 Pushing A Notification
The process of sending notifications follows a 3-step approach.
  1. What - You can define the notification content using either a interface or APIs exposed by the service provider.
  2. When - You may choose to send the notification immediately, basis action/trigger or at a scheduled time.
  3. To whom - You can define the audience to whom you would want to send notifications. The audience filters are typically managed by the service provider, and provide options to send notifications to all, to a specific subscriber, to a segment of subscribers.
Trigger notifications to capture marketable moments. Automate your notification campaigns with iZooto. Learn more.
Web Push notifications can be targeted and personalised to select segments of your user base, and even personalized for specific users. As compared to email or SMS, in the context of web push, users are not required to do away with their personal information. Segmentation basis a user’s browsing and purchasing pattern ( events and properties ) can used to create powerful audience segments. Marketers / developers would need a interface for writing messages, selecting the target audience and pushing or scheduling notifications.
Publishers can build repeat traffic by leveraging web push notifications. They can build this infrastructure themselves, or leverage existing tools such as iZooto. Increasingly, web developers opt for iZooto for these services instead of building them, so that they can focus on building their web apps. Building and maintaining a cross-platform web push notification service is bound to consume significant resources and time. SaaS Platforms such as iZooto are best suited because:
2.6 Which browsers support web push notifications?
Currently, only Chrome, Firefox on Android OS, Windows, OS X, Linux and Safari on OS X support web push notifications. All Chromium based browsers also support web push notifications. None of the browsers support web push notifications on iOS.
On Desktop or the large screen, web push notifications are supported by Chrome, Firefox and Safari across Windows, Mac OS and Ubuntu.
For example - while segmenting your subscriber base by their recent activity, it can you help you identify your most active and dormant subscribers. Further, pushing out personalised notifications to subscribers will help build a strong recall and encourage loyalty amongst them. It could also allow you to send follow-up campaigns to your most unengaged subscribers — the ones who haven’t done any activity in the past few days.
Device OS Browser
  • Mobile
  • Android
  • iOS
  • Chrome 42+, Firefox 48+
  • No Support
  • Desktop
  • Windows
  • Ubuntu (Linux)
  • Mac OS
  • Chrome ( 42+)
    Firefox ( 44+)
    Safari ( 9.3, 10)
  • Tablet
  • Android
  • iOS
  • Chrome 42+, Firefox 48+
  • No Support
Desktop vs Mobile
Desktop Mobile
Permissions Opt-in Required Opt-in Required
Character limits for notification Depends upon the screen size, width, and the input language selected. Depends upon the screen size, width, and the input language selected.
Direct app open Yes Yes
Deep link support Yes Yes
User control Yes Yes
Image support Chrome only Chrome only
Badge Starting Chrome 53 Starting Chrome 53
Sound support No No
Payload limit 2 kilobytes 4 kilobytes
Interactive buttons Only for Chrome Web Push Limited to 2 Only for Chrome Web Push Limited to 2
Feedback Not from an app, rather through APNs Feedback Server Yes, response from the App/Device
Direct app feedback on delivery No Yes
Device management Notifications are displayed when delivered. No Notification Center Notifications are displayed on lock screen and are available in the notification tray
Two way messaging support Upcoming Feature in Chrome Upcoming Feature in Chrome
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2.7 Can an HTTP website support web push notifications?
By default, web push API can only be used by websites operating on HTTPS protocol. For websites operating on HTTP protocol, subscribing to web notifications is a 2-step process. The subscription process involves the user subscribing to a secure subdomain such as yourdomain.izooto.com or notify.yourdomain.com. Since this is a two click process, the opt-in rates are far lower as compared to HTTPS, hovering around 1% - 3%.
2.8 Permission UX: The right way to ask for permission from a user
It is important that users are convinced to subscribe to notifications before they are prompted. There are multiple ways of educating the end user. Here are some of the recommended approaches :
  1. The user should show intent before a site asks for permission : Most of the marketers and developers commit the mistake of asking permission on page load time. This is not an ideal experience and impacts the opt-in rates adversely resulting in more users actually blocking than allowing for notifications.

How do people respond to web push notifications?

3.1 Understanding Subscription Rate of Web Push Notification
One of the most frequently asked questions is how many users subscribe or opt-in for web push notifications. All the leading browsers - Chrome, Firefox, Safari, Opera and other Chromium-based browsers now support web push notifications. The permission or opt-in process is similar across the browsers. Users are required to grant explicit permission to a website (web app), hence opting-in to receive push notifications. It is important to understand that the capability of web push notifications is only for websites operating on HTTPS protocol ( with an SSL certificate. Subscription or opt-in rates usually vary from anything between 5% to 10% of total unique visitors, depending upon the implementation. Marketers often use a double opt-in process to ensure that users opt for notifications instead of blocking them. To convert your website visitors into subscribers, it is critical to design the right subscription UX with web push notifications.
3.2 Understanding User Response of Web Push Notification
Click-through rate for push notification is defined as the number of clicks on a notification divided by the number of subscribers who have viewed the notification. Marketers often use Notifications Clicked / Notifications delivered to calculate CTR's. For example, if a notification is delivered to 100 subscribers and receives one click, then the click-through rate for the notification would be 1%. Most marketers use this metric to understand the effectiveness and success of their push notification campaigns. There is no pre-set benchmark of click-through rates of push notifications. CTR's of push notifications depend on multiple factors including -
3.3 Targeted Notifications vs General Broadcast Notifications
‘One size fits all’ doesn’t work very well with Web Push Notifications. Assuming that all subscribers will have the same preferences can result in a high number of users unsubscribing from notifications. It’s common knowledge that sending targeted notifications can help you engage better and get higher click rates. Also by narrowing your focus and targeting selective segments, your subscribers will find your notifications to be much more relevant and keep them from churning away.
For example - while segmenting your subscriber base by their recent activity, it can help you identify some of your most loyal subscribers. It could also allow you to send follow-up campaigns to your most unengaged subscribers — the ones who haven’t done any activity in the past few days.
Similarly, if you planned to target recent subscribers with a “Subscription Date” segment, you might encounter higher engagement and lower bounce rates (due to definite recall) than you would if older subscribers were targeted. Click Through Rates on notifications targeting a specific audience can be as high as 40% also.

What can you use Web Push notifications for?

4.1 Understanding the Impact of Web Push Notifications
While the adoption of web push notification has been nothing short of crazy, the question on the impact of web push implementation still exists in the minds of marketers.
Well, here is the short answer – No.
There is no negative impact of implementing web push notification. The fact that Google has been pushing for it aggressively, definitely suggests that there is no possible negative impact.
Read this detailed data-driven post on the impact of Web Push Notifications on SEO.
4.2 Industry wise use cases
Learn more about industry-specific use cases.

How to create an effective Web Push notification strategy

5.1 Best Practices
An effective Web Push Notification campaign can easily outform Email Marketing when executed well. Here are tips you can follow to ensure that your web push notification campaign is a success:
Personalization - Personalized messages teamed up with behavioral data perform much better. The messages are highly targeted, timely, and personalized. For example: An eCommerce site sends you a message that those shoes you were browsing last week are now available in your size. When you tap in, the message takes you right to the product page for the shoe with your size checked.
Add Call To Action Buttons - A Call-to-action (CTA) can be added to provoke an immediate response, usually using an imperative verb such as "Buy now", "Know more" or "Share on Twitter".
Push Notifications with Images - We all know “a picture is worth a thousand words”. Notification with an image and call-to-action is worth a lot more than that. Along with call-to-action buttons, Chrome Rich Notifications capture mobile user’s attention and offer powerful ways to interact with push notifications, providing more data for personalization and creating refreshing experiences for users.
Location based targeting - While subscribing to notifications, there are few properties that are captured by-default at the browser end - with one of them being Location. Websites can use location data combined with behavioral data to send relevant notifications such as -
Time Zone Based Delivery of Push Notifications - Internet is everywhere and so are your users – prospects and clients. Clearly, you can no longer afford to ignore that “international-time zone-user-set”. Especially, in such cases, communicating with users across different timezones is a key challenge. More than often marketers not paying heed to this, end up irritating customers. End result – user churn. It is for this reason, understanding your audience is extremely critical. There is fair amount of sensitivity attached to receiving notification on the wrong time – we help you take cognisance of that.
5.2 The Don'ts

Should I build my own Web Push Solution or use a 3rd party service provider?

There are couple of points to keep in mind before taking that “Make or Buy” decision. Building a web push notification platform will, in fact, make it a second product altogether within your core business - a product that demands continuous resources to -
When making that rather important “Make or Buy” decision, ask yourself - are you ready to put in that amount of resource, time and money?
Your sheer focus rightfully needs to be spent on your core business/product, which, as we all know pretty well, isn’t web push notifications. So why not let the “others” take care of it, the ones for whom building web push notifications is the core product? They’ll help you do a much better job at it, don’t you think?
6.1 Checklist for selecting a 3rd party push notification provider
Compatibility
Segmentation
Features
Support
Reporting
6.2 History of Web Push Notifications
  • June 2009
    Apple launches Apple Push Notification Service (APNs), the first push service.
  • April 2015
    Chrome introduces Service Workers and supports Web Push API with Chrome 42
  • Dec 2015
    Chrome introduces Custom Notification Buttons with Chrome 48.
  • Jan 2016
    Firefox rolls out web push support with Firefox 44 for Desktop
  • May 2016
    Microsoft Edge Releases support Service Workers
  • Aug 2016
    Firefox extends web push API support for mobile with Firefox 48
  • Feb 2017
    Chrome introduces Rich Notifications with Chrome 56
  • April 2017
    Native Chrome Desktop Push Notifications in Mac OS with Chrome 59
  • Oct 2017
    Chrome deprecates usage of notification permission from insecure iFrames with Chrome 62