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Build a WhatsApp like Chat app in Android & iOS & Know How WhatsApp Works Technically

WhatsApp is the most sought after messaging application that has revolutionized the messaging app market. Several attempts have been made in vain to clone WhatsApp as a chat app, but none of them yielded the result. Despite introducing similar functionalities, no chat app has ever been able to topple WhatsApp’s supremacy as a chat app.

In order to build a WhatsApp like chat application, one should have a detailed understanding of its functioning mechanism and technicalities.

How Whatsapp Messaging App is Working Technically?

create a clone app similar to whatsappWhatsApp uses Ejabberd (XMPP) server which facilitates instant message transfer between two or many users on a real-time basis. High reliability and sustainability even under peak traffic the reason why WhatsApp developers chose Ejabberd above anything else.

ERLANG is the programming language used to code WhatsApp. Code restructuring and some important changes were made to the Ejabberd server to achieve optimal server performance.

Further, Erlang is agile to adapting to instant updates and hot fixes. This is what helps WhatsApp to quickly push the changes to live implementation without requiring restarts.

1. Insights on data transfer in WhatsApp

how whatsapp works technicallyWhatsApp manages over 50 billion messages a day. The key to smooth data processing lies with the message queue length. The length of the message queue of all the processes associated with a node is monitored.

In case of multimedia messages, contents (audio, video, or image) are uploaded into a HTTP server and are linked with the content and then sent to the receiving node (receiver) in the form of a thumbnail. Based on the user’s preference the content can either be viewed or discarded.


2. Protocol used by WhatsApp

The primary protocol in use is XMPP (Extensible Messaging and Presence Protocol).DSL ensures network security and also helps in preventing private data transfer.

As and when message is sent, it is queued on the server. The message waits in the queue until the recipient reconnects to receive the message. As and when a message is delivered the sender gets notified by a double check mark near the message. After the delivery the messages are instantly deleted from the server memory.

This instant deletion from server memory helps WhatsApp keep its resources to a bare minimum.

Additionally, Whatsapp uses HTML5 WebSockets which communication technology which facilitates two-way communication.

3. Registration process of WhatsApp

Whatsapp Registration ProcessUsers can register for WhatsApp by entering their mobile number. On entering the number, the user will be sent a OTP which once verified by the device will initiate the user to the chat screen.

4. Database management

Mnesia DB handles the heavy-duty task of database management. Mnesia is a multiuser distributed DBMS which also happens to be the default DB of ERLANG. Mnesia helps achieve quicker request responses, thereby improving the overall efficiency.

FreeBSD is the OS upon which WhatsApp is built. Improvising on the ERLANG based applications and optimizing FreeBSD, WhatsApp is able to achieve better performance. For storing multimedia files, the app uses an exclusive web server YAWS.

Catch a Similar App like WhatsappRequest a Demo


Build a Whatsapp like Messaging App with Contus Fly

Having discussed the technicalities of WhatsApp it is time to shift gears over analyzing the possibilities of creating a whatsApp alternative. There are plenty of messaging applications in the market that appear to be perfect WhatsApp clones. The reality is many of the attempts of building WhatsApp like apps are failing because they do not follow the technical aspects.

Well, if we take such apps as an example, it might be quite difficult to understand as they are completely built products. Instead a ready made solution that can help in creating a WhatsApp clone app would be a better learning material.

Contus Fly is a framework that catalyses the build a chat application. Contus Fly can be used to develop WhatsApp clone app for Android, iOS and Website platforms as it has the SDK ready for these widely preferred mobile operating systems. Since native coding has been used by Contus Fly to achieve better speed, it can be handy in developing a WhatsApp like native app.

Framework & Architecture of Contus Fly

contus fly real time chat app work flow


Ejabberd, the open source Jabber server has been customized by Contus Fly to improve operational efficiency. The XMPP protocol has also been customized to speedup signing in and re-signing in sessions. To protect the app from DDOS attacks and to prevent account spoofing, this mobile chat app solution has been encrypted with HMAC.

Mnesia and MySQL

For data storing, Contus Fly makes use of both Mnesia and MySQL. While Mnesia is used to maintain user login sessions, MySQL contributes in maintaining the user details, right from account credentials to other personal data.

Cassandra database

Chat logs are a key for instant messaging applications. In order to save chat history between several nodes, Contus Fly has deployed . This database offers a good read write speed thus helping users to retrieve chat logs as and when they need.

Amazon S3 bucket

Multimedia messages including audio, image, video are saved in Amazon S3 bucket. Registration for the app usage can be done in multiple ways including mobile number, email, user name password and social login.


WebRTC is a source code that is used to build real-time communication (RTC) in browsers and mobile app. Contus Fly has inbuilt WebRTC that allows its users to have VOIP (voice over the internet protocol) voice/video calls in their messaging app


Contus Fly offers a 3 layered security flow – end-to-end encryption, HMAC authenticated screening, and online/offline verification protocol; that ensures the data transmitted within the chat app is secure.

As and when a user triggers a message, the chat app SDK sends a request to the Ejabbered server. In return the server checks for the availability of the recipient and if available, the delivery request is sent to the recipients SDK and then delivered. If the recipient is offline, the data is stored in the Ejabbered as message will be queued in the server.

Contus Fly Features

  • Group Chat
  • Offline Messages
  • Push Notifications
  • Presence
  • Social Integrations
  • Locations
  • Sync and Store
  • Voice Calling
  • Video Calling Integration
  • Multimedia Sharing
  • Easy Screen Sharing
  • Fully Searchable
  • Secure
  • Support

Uses Cases of Contus Fly

1. Build Your Own Chat App:

Contus Fly is a instant messaging solution that can be customised according to the needs of the user. The customizations are highly flexible and can be made both initially or even after the app is launched.

2. Chat API:

Chat API provides users the access to infrastructure of server. This enables any website or app to be integrated with a messaging solution that performs without any hassles and is highly scalable.

3. Messaging SDK:

SDK is an instant messaging framework that enables the app built with it to work on specific platforms. Contus Fly’s SDK has been built in an enterprise grade making it compatible on android, iOS and windows.

4. In-app Messaging:

A source to connect with your customers goes a long way. In-app messaging and push notifications initiates a direct conversation with app visitors and assists in providing accurate product explanation and suggestions.

Contus Fly – A Premium Solution to Create Real Time Chat & IM Apps

  • 100% Customizable Solutions
  • Multi Platforms Supports
  • Authenticates using Social Networks


Leave a Reply

142 Comments on "Build a WhatsApp like Chat app in Android & iOS & Know How WhatsApp Works Technically"

1 year 2 months ago

can u please help me in code of how to send push notifications from ejabberd server to android app when app is offline like we receive notifications in whatsapp and facebook

1 year 3 months ago

Do u have an app such as what’s app clone? In All The other apps available the clone remains maximum for a day and then it again asks to scan the code. Do u have or do u know any other app in which unless I logout from the clone what’s app it doesn’t disconnect or asks for the qr code?

Girish Soni
1 year 3 months ago

why we use erlang or mnesia we use simple airthmatic operation in any language and mnesia also exchange by mysql…

Anthony J
1 year 4 months ago

Please I need someone who can develop a whatsapp-like app. If u can get me someone who is good with erlang I will be happy, thank you.

1 year 4 months ago

Hi Ramanthan, i have one doubt.. if whatspp is not storing text messages in their server after it is sent..then how the cyber cell monitors the unwanted messages in whatsapp??
Can u pls explain it technically.?

1 year 5 months ago

Hi, recently I came to know about DUTA service in whatsapp that helps to obtain latest news, entertainment, sports etc. Can you make a similar service like this in your instant messaging chat app?

Emely Linton
1 year 5 months ago

Do you have any expertise in building a real time chat app before this clone app?

1 year 6 months ago

i am confuse which server is best for .is gcm or that all sources which use for built app..please help me to understand this and how i use that all source?

1 year 6 months ago

I want to create an app like whatsapp where I want to include peer-to-peer voice calling feature. Is that possible using your solution?

Dan McKinley
1 year 6 months ago

What will be the market cost for developing a whatsapp clone?

Vinoth Paulraj
1 year 6 months ago

Hi Ramanathan,

Its Really amazing article for people like us. I’ve a doubt , can we clone the whats app with different configurations like language will be Java , server will be Apache Tomcat or Jboss ? Because you defined each and every technologies for improving the performance of whats app so changing the technologies will give impact on the application ?

1 year 7 months ago

What Is price for white label chat app like whatsapp

1 year 7 months ago

Why Erlang was chosen for WatsApp?? If instead at server side the implementation was in C++ then how will you rate the performance and hardware usage/requirements for Erlang vs C++ ??

Binu Madhav
1 year 8 months ago

I didnt understand your business model, I have few questions:
1. Is it like this, we give a requirement, you make the modification for the clone, and host it, we pay monthly?
2. Will you provide the source code?
3. Who will manage the security issues like hacking threats?
4. Can we brand it in our name? Can we host the app in platforms like PlayStore in our name?
Sorry, I am new to it, so these questions.
Thanks in advance.

1 year 8 months ago

Hi Binu,
1) It is a one-time payment.
2) If you want to develop the chat app for your business, We will provide full access to source code.
3) After the development, we provide the technical support as long as you need!
4) Yeah, It’s Whitelabel Solution.

1 year 8 months ago

Hi: do you know if group data (name of the group and members) are stored in the whatsapp servers? Or are also a app-side?

1 year 8 months ago

I wanted to develop a chat application exclusively for my corporate purpose. Can you customize and give the required features for internal office communication?

1 year 9 months ago

Hi Ramanathan, how does one create settings similar to those on WhatsApp where one can change their account name and mobile no?

1 year 10 months ago

during the backup of my chats & images the backup is not completing successfully on my shows massege like unfortunately whattsapp not responding.

1 year 11 months ago

hi sir
could u provide the time taken of a message to travel from one phone to another. factors affecting it and how we can measure the latency?

Allan Gondwe
2 years 9 days ago

Halo Ramanathan!

I intend to use WhatsApp for my private business with a company well known to everyone and I need a private discussion with an expert like yourself. How can I do that?