• Browser Push Notification

What is GCM and FCM? (Differences and Limitations)

Last updated on Aug 10, 2020

Read More

What is GCM and FCM? (Differences and Limitations)

What is GCM (Google Cloud Messaging)?

Google Cloud Messaging is a free service that enables developers to send messages between servers and client apps. This includes downstream messages from servers to client apps, and upstream messages from client apps to servers. It was launched in 2012 with a goal of making it the best mobile messaging platform to help marketers reach their users, notify them of important events and keep the data in their applications fresh. GCM is being used by marketers and developers to send messages to their users with the help of GCM Sender ID and the Server Key.

Google Cloud Messaging (GCM) Sender ID: A unique numerical value which is created when you configure your Project in the Google Developers Console/ Google Cloud Console. The Project Number is GCM Sender ID and this is used in the registration process to identify an app server that is permitted to send messages to the client app.


GCM, while showing an amazing growth, is an integral part of any application these days. Messaging is a feature that almost every developer needs and uses for engaging with his users. Push notifications enabled have almost 3X higher attention and 88% more app launches, which means more user engagement. 

Two main aspects of any messaging platforms are Reliability and Low Latency.

Firebase Cloud messaging (FCM)

Firebase is a mobile platform that helps you quickly develop high-quality apps, grow your user base, and earn more money. Firebase is made up of complementary features that you can mix-and-match to fit your needs. As announced at Google I/O, Google Cloud Messaging Platform will get replaced by Firebase Cloud Messaging. The new mobile development platform, Firebase, is a suite of integrated products which are designed to help you develop your application. Read more about Firebase here.

Earlier limitations with GCM, but NOT ANYMORE!

Unlike GCM, Firebase can help you build an app, with features that work together, all in one place, packaged into a Single SDK.
These new SDKs are designed to make the integration with FCM much, much simpler. Firebase Messaging SDKs for Android and iOS take away a lot of boilerplate code away from you such as registration logic, subscribing to topics, handling any errors you get with the servers while doing these actions. All this is now being taken care automatically.

These are all the permissions that you had to worry about before with GCM. Not anymore!

Difference between GCM and FCM

Same reliability with a much more Simplified SDK

  • The new SDKs, are really simple APIs to start using FCM and reach multiple platforms.

  • Seamless integration with other Firebase products like Firebase Analytics, making it easier for you to develop, grow, and earn from your applications

Then, what's new with FCM?- 


  • New FCM libraries- These libraries use manifest merging, so you don't have to worry about permissions. It automatically adds any permission that is needed reducing the amount of effort you need to put in.
  • Simplified registration flow.- You are well aware that a registration token is an address that FCM uses to deliver the message to a device. Now this process has become asynchronous. Google libraries automatically get a token on your behalf so, when you make a request to 'get token', you receive an already registered token. All you have to do is, send this to your servers, and start sending messages.

All these new improvements apply to both Android and iOS SDKs. In addition to having SDKs for iOS and Android, a brand-new SDK for  developers using C++ is also getting launched soon.

Additional Features

  1. Analytics- Firebase provides free and unlimited analytics solutions helping you gain insights about your users 'ad click' & 'app usage'. Firebase Analytics works together with other  firebase features so you can take action on everything from click-through rates to app crashes.

  2. Firebase Remote Config- It is a simple key-value store that lives in the cloud and helps you deploy changes that your app can read within a matter of minutes. In addition to the basic feature, Firebase remote config also has an audience builder that helps you create custom audiences and perform A/B testing.

  3. Easy Implementation- Firebase is quick and easy. With intuitive APIs packaged into a single SDK, you can focus on solving your customer's problems and not waste time building complex infrastructure.

  4. Cross-platform support with APIs packaged into single SDKs for iOS, Android, JavaScript and C++. Expand to different platforms without modifying your infrastructure.

  5. Web Push support- With FCM, you can now implement the standard IETF Web Push APIs and start targeting your browsers.

    For example, on Chrome, you can send a message to your Chrome page in Windows, Mac, or Linux, and you can also target your Chrome on Android. 

    Some added features-

    Topic messaging allows you to send a single message to a large number of devices. It's a great way to notify your users that are interested in common topics, like a musician or an artist or a game or a sports event. All you have to do is publish a message to FCM, and FCM delivers it to all the devices subscribed to this topic. There is no limit on topic messaging. Now you can have as many subscribers on a single topic, or across different topics, in your application. All you have to do is set the topic name in the "to" parameter.  

    Sending a message to a combination of topics-
    Let's say you have a weather application, and you want to send weather updates to your users. Now, some of your users might be subscribed to a topic for Mumbai weather, and some might be subscribed to a topic for Delhi. So when there is a weather update, you don't want to publish the same message on both these topics, as there might be an overlap, and some users will get duplicate messages. 

    Now you can use our brand-new API to specify a condition, and FCM will make sure you only deliver this message to users that qualify this condition. Here with the new API, the message will be published to users that either has the Mumbai weather or the Delhi weather So it's a union. Note- You can also hit an intersection of by using the "and" operator. and categorize them into topics based on your users

You can use you FCM Sender ID and Server key to get started with iZooto Web Push Notifications.


All Posts
Ruchika Sharma
Ruchika Sharma
Ruchika Sharma, the Product Marketer at iZooto is an Art Lover & Creative Writer who likes to sketch in her free time. She dreams of travelling the world someday, all by herself. To connect with her, follow her on Twitter: @Sh_ruchika

Related Posts

Meta Going The TikTok Way Puts News Publishers In A Spot

Not long ago, news and media publishers were investing significantly i[...]

iOS Web Push Notifications: What Does This Mean For Publishers?

Apple announced support for web push notifications for Safari on iOS s[...]

The Rise Of Machine Learning In The News And Publishing World

Technology has accelerated production and efficiency across most indus[...]

  • 4 min read
  • Aug 05, 2022