Chat App System Design & Architecture : Key Insights For 2023
Explore the most important insights on the chat app architecture when building your own messaging application from scratch or adding chat functionality to your existing apps.
Table of Contents
Introduction
Whether your users are collaborating with their colleagues or simply keeping in touch with their loved ones, chat apps are the go-to mode of communication to anyone these days. They are easy to use, and create a sense of instant connection that no other technology could match.
And if you are looking to build one such messaging application for your business/ service, I’d urge you to understand the architecture and its system design of a chat application as a first step. This will dramatically help you in streamlining the development process and save you huge energy, cost and time.
In this article, we will discuss in detail about the chat app architecture and equip you with the knowledge you need to seamlessly integrate chat into your Android, iOS or web apps.
Chat App Architecture
Chat app architecture is the complete design and structure of a chat app. It comprises the front-end and back-end components that interact with each other to enable sending and receiving of messages in real-time.
The Building Blocks of a Chat Application

As a whole, a chat app system design is a complex structure that is sometimes not easy to understand. But, when this structure is broken down into nuts and bolts, it becomes the most simple technology to understand and develop. So, in this section I will dismantle the different components of a messaging application and explain them briefly.
In-app Chat Server
The In-app chat server is the backend of your application that your users do not have direct access to. Rather, this centralized location is where the communication between the clients takes place. The chat server acts as a mediator between the clients of the users’ application, streamlines the exchange of chat, and manages the chat data.
There are also other functionalities that a chat server performs. Here is a quick list of them:
- Facilitating real-time communication between multiple clients
- Creating and managing chat rooms or channels
- Handling user authentication and authorization
- Providing a centralized location for message storage and retrieval
- Implementing various types of chat protocols, such as TCP or WebSocket
- Scaling to accommodate large numbers of users and high-traffic volumes
- Monitoring server health and performance
- Enforcing chat room rules and policies, such as maximum message length or prohibited content
- Facilitating moderation tools for chat room administrators, such as muting or kicking users
- Providing analytics and insights on chat room activity, such as user engagement or message frequency.
In-app Chat Client
The client side of the messaging architecture in a chat app is what your users will see and interact with. The chat client is typically the application installed on the users’ desktop, web, or mobile. It communicates with the operating system of the user’s device and transmits the message data to the chat server.
Below are the list of functionalities that a chat client will perform when you build a chat app
- Sends and receives messages in real-time
- The ability to create and join chat rooms or channels
- Options to search for and add friends or contacts
- The ability to block or report users who are behaving inappropriately
- Notifications for new messages or mentions
- Emojis and other expressive features to enhance communication
- The ability to send files, such as images or documents
- End-to-end encryption for privacy and security
- Audio and video chat capabilities
Ready to Get Started with Our Self-hosted Video, Voice & Chat Solution?
- 100% Customizable
- One-time License Cost
- Hire Dedicated Team
Chat REST API
As the name indicates, the Chat REST API is entirely an interface that uses the REST protocol when you build an app or online chat system/ platform. The REST protocol of your API is nothing but the architectural style that helps your app make and receive requests and responses using the HTTP methods like GET, POST, PUT and DELETE.
So why do we use the chat REST API?
Simple as that, it creates endpoints (specific URLs) that developers can use to access the chat functionalities.
Developers can make HTTP requests to these URLs using methods like GET, POST, PUT, and DELETE to perform various chat-related operations, such as:
- Sending messages
- Retrieving message history
- Accessing user profiles
- Updating chat settings
Each endpoint refers to a specific action or resource in your chat system, and the API documentation will provide details on how to use each of them, including the required parameters and expected responses.
WebSockets Server
WebSockets in a chat app design are used for implementing bi-directional communication between the server and client. When you use a traditional communication architecture, it uses HTTP to make the client request to the server. This approach is not very efficient when continuous message requests have to be placed.
This is where you will need a WebSocket Server to enable the server to send data to the client without the need for a request.
Data Storage
Chat apps are not only about text messages. Users exchange media like images, videos, file, emojis and gifs with each other, almost on a daily basis. But where do all these data get stored?
Well, you’ll need media storage where user information like profile details and media data can be ciphered and stored safely. It’s important to note that chat apps come in all shapes and sizes, and the size and functionality of your chat client and server will depend on the intended use of your app.
In the architecture and system design, you could even opt for a hybrid approach, using a robust relational database for storing generic data like profile settings, while making use of a NoSQL database like Cassandra for storing messages. Since NoSQL databases are optimized for low-latency data access and horizontal scaling, they’re ideal for storing messages.
Chat Application Architecture Diagram

Features and Functionality of a Chat App
In the above section, we discussed the primary components of a chat app design. Going ahead, we will explore some of the modern chat app features that you must include in your chat apps.
User Registration and Authentication: It is very essential that your chat app allows only authentic users. For this, you will need to register the user by a sign-up process and verify their account with your app using their email address or phone numbers.
This ensures no third party attacks or malicious encounters happen on your app.
One-to-one or Group Messaging: The foremost feature of a chat system design is the ability to send and receive messages. It can be peer-to-peer (1:1) or group chat as per your users requirements.
Push notifications: Don’t let your users miss out on any incoming message/ reaction. Alert them from time to time on their device’s notification pane, and draw attention and engagement effortlessly.
Personalization and user settings: Everything is customizable these days and chat apps are not an exception. Give your users to leverage creativity and fun in their own style with font colors, themes, background colors, profile photos and more.
Read Receipts: Create a sense of urgency and user retention by showing them that the message they’ve sent to others have been delivered successfully and read by them.
Media Shares: Plain text messages are outdated. Users have moved on to images, audio, video, emojis and gifs for interesting conversations.
This indeed is not over. There are plenty of chat features that you can consider adding to your app for building modern messaging experiences!
So, you now know what features to add when planning the dev process of your chat application and its system design, but which framework and technology should you build them on?
Let’s get into the details now!
Backend Programming Languages:
There are plenty of programming languages out there to build a messaging app. But you’ll need to find which one of them is right for the front-end and back-end of your app’s use case.
Here is a list of the best backend programming languages that can be used to build a chat infrastructure.
Backend Programming Languages:
Languages | Pros | Best for |
Erlang | Concurrency, scalability, and reliability | Large-scale messaging apps |
Scala | Scalability and multi-threaded functionality | Social media and messaging apps |
PHP | Great for web applications | Websites and small-scale messaging apps |
Java | Popularity and versatility | Enterprise-level messaging apps |
JavaScript (Node.js) | Front-end and back-end can be written in the same language | Cross-platform and real-time messaging apps |
Frontend Programming Languages:
Languages | Pros of the Language | Best for (Industries Served) |
JavaScript | Easy to learn, versatile, cross-platform compatibility | All types of industries, web-based chat applications |
Swift | Provides a native iOS feel, fast and powerful | iOS-based chat applications |
Kotlin/Java | Provides a native Android feel, fast and efficient | Android-based chat applications |
Messaging App Frameworks
Many frameworks and tools are available that are designed to incorporate chat functionality into new and existing applications. Choosing which frameworks to use when making a messaging app should not be taken lightly, as this decision can either save or cost you hundreds of developer hours.
When you build chat functionality into your new or existing apps, you can choose any framework or tool from hundreds of options available in the market. However, you need to put some serious focus on choosing the right framework for your app, as it highly impacts the cost and time of your app development.
Here are a few of the components you must carefully choose:
Chat Protocols
A chat protocol is a set of rules that will define how your messaging app installed on different user devices will communicate with each other. These protocols enable different messaging apps to exchange data and messages seamlessly. Some of the popular chat protocols used in messaging apps include:
XMPP (Extensible Messaging and Presence Protocol): It is an open-source protocol used for instant messaging and presence information. XMPP is highly extensible and supports a range of features, including group chats, voice and video calls, and file transfers.
MQTT (Message Queuing Telemetry Transport): MQTT is a lightweight protocol used for the Internet of Things (IoT) and real-time communication. It is designed to be highly efficient and supports both push and pull messaging models.
WebRTC (Web Real-Time Communication): WebRTC is an open-source protocol used for real-time audio and video communication over the Internet. It provides a range of features, including video and audio calling, screen sharing, and file transfer.
Chat SDK
A Chat SDK (Software Development Kit) is a pre-built set of tools and libraries that help developers integrate chat features into their applications. The SDK includes everything from messaging interfaces to server-side APIs that handle chat exchange between users, real-time notifications, and more.
MirrorFly Chat SDK: The Best Option To Build Messaging Apps
MirrorFly is a leading in-app communication provider that offers a wide range of features and functionalities via its chat SDK. It includes chat APIs for instant messaging, audio, and video calls, real-time presence indicators, read receipts, and file sharing. The SDK is highly scalable, making it an ideal choice for apps with high user traffic. It supports multiple chat protocols, including XMPP, MQTT, and WebSockets, making it compatible with a wide range of messaging apps.
In addition, MirrorFly Chat SDK is available as a SaaS product for a recurring monthly subscription and as a self-hosted chat solution for a one-time license cost. Here are a few of the perks of the SDK you must never miss out on when designing a chat application!
MirrorFly Cloud Solution (SaaS)
- Free chat solution provider
- Lets you host your chat app on a dedicated cloud server
- Offers 21-day FREE trial of voice and video call SDKs
- Supports multi-tenancy
MirrorFly Self-hosted Chat Solution (SaaP)
- Provides 100% customizable video, voice, and chat SDKs
- You can avail lifetime access to features for a one-time license cost
- Lets you conveniently host your app on-premise
- Offers white-label solution
So why wait, get started with the #1 Chat solution and build the most competitive chat app and its system design!
Conclusion
In conclusion, designing a chat app architecture can sometimes be a daunting task, but with the right frameworks and protocols, the development becomes much easier. In addition to this, pre-built UI kits with SDKs like MirrorFly make building a chat app easy and effortless.
If you are just getting started, MirrorFly’s Free chat SDK can be a good place to start with!
And now, I’ll bid my bye and get back with yet another interesting article soon. Until then, post in your comments and queries about designing a chat system below, and our team of experts will be happy to help you anytime!

Explore the most important insights on the chat app architecture when building your own messaging application from scratch or adding chat functionality to your existing apps.
Table of Contents
Introduction
Whether your users are collaborating with their colleagues or simply keeping in touch with their loved ones, chat apps are the go-to mode of communication to anyone these days. They are easy to use, and create a sense of instant connection that no other technology could match.
And if you are looking to build one such messaging application for your business/ service, I’d urge you to understand the architecture and its system design of a chat application as a first step. This will dramatically help you in streamlining the development process and save you huge energy, cost and time.
In this article, we will discuss in detail about the chat app architecture and equip you with the knowledge you need to seamlessly integrate chat into your Android, iOS or web apps.
Chat App Architecture
Chat app architecture is the complete design and structure of a chat app. It comprises the front-end and back-end components that interact with each other to enable sending and receiving of messages in real-time.
The Building Blocks of a Chat Application

As a whole, a chat app system design is a complex structure that is sometimes not easy to understand. But, when this structure is broken down into nuts and bolts, it becomes the most simple technology to understand and develop. So, in this section I will dismantle the different components of a messaging application and explain them briefly.
In-app Chat Server
The In-app chat server is the backend of your application that your users do not have direct access to. Rather, this centralized location is where the communication between the clients takes place. The chat server acts as a mediator between the clients of the users’ application, streamlines the exchange of chat, and manages the chat data.
There are also other functionalities that a chat server performs. Here is a quick list of them:
- Facilitating real-time communication between multiple clients
- Creating and managing chat rooms or channels
- Handling user authentication and authorization
- Providing a centralized location for message storage and retrieval
- Implementing various types of chat protocols, such as TCP or WebSocket
- Scaling to accommodate large numbers of users and high-traffic volumes
- Monitoring server health and performance
- Enforcing chat room rules and policies, such as maximum message length or prohibited content
- Facilitating moderation tools for chat room administrators, such as muting or kicking users
- Providing analytics and insights on chat room activity, such as user engagement or message frequency.
In-app Chat Client
The client side of the messaging architecture in a chat app is what your users will see and interact with. The chat client is typically the application installed on the users’ desktop, web, or mobile. It communicates with the operating system of the user’s device and transmits the message data to the chat server.
Below are the list of functionalities that a chat client will perform when you build a chat app
- Sends and receives messages in real-time
- The ability to create and join chat rooms or channels
- Options to search for and add friends or contacts
- The ability to block or report users who are behaving inappropriately
- Notifications for new messages or mentions
- Emojis and other expressive features to enhance communication
- The ability to send files, such as images or documents
- End-to-end encryption for privacy and security
- Audio and video chat capabilities
Ready to Get Started with Our Self-hosted Video, Voice & Chat Solution?
- 100% Customizable
- One-time License Cost
- Hire Dedicated Team
Chat REST API
As the name indicates, the Chat REST API is entirely an interface that uses the REST protocol when you build an app or online chat system/ platform. The REST protocol of your API is nothing but the architectural style that helps your app make and receive requests and responses using the HTTP methods like GET, POST, PUT and DELETE.
So why do we use the chat REST API?
Simple as that, it creates endpoints (specific URLs) that developers can use to access the chat functionalities.
Developers can make HTTP requests to these URLs using methods like GET, POST, PUT, and DELETE to perform various chat-related operations, such as:
- Sending messages
- Retrieving message history
- Accessing user profiles
- Updating chat settings
Each endpoint refers to a specific action or resource in your chat system, and the API documentation will provide details on how to use each of them, including the required parameters and expected responses.
WebSockets Server
WebSockets in a chat app design are used for implementing bi-directional communication between the server and client. When you use a traditional communication architecture, it uses HTTP to make the client request to the server. This approach is not very efficient when continuous message requests have to be placed.
This is where you will need a WebSocket Server to enable the server to send data to the client without the need for a request.
Data Storage
Chat apps are not only about text messages. Users exchange media like images, videos, file, emojis and gifs with each other, almost on a daily basis. But where do all these data get stored?
Well, you’ll need media storage where user information like profile details and media data can be ciphered and stored safely. It’s important to note that chat apps come in all shapes and sizes, and the size and functionality of your chat client and server will depend on the intended use of your app.
In the architecture and system design, you could even opt for a hybrid approach, using a robust relational database for storing generic data like profile settings, while making use of a NoSQL database like Cassandra for storing messages. Since NoSQL databases are optimized for low-latency data access and horizontal scaling, they’re ideal for storing messages.
Chat Application Architecture Diagram

Features and Functionality of a Chat App
In the above section, we discussed the primary components of a chat app design. Going ahead, we will explore some of the modern chat app features that you must include in your chat apps.
User Registration and Authentication: It is very essential that your chat app allows only authentic users. For this, you will need to register the user by a sign-up process and verify their account with your app using their email address or phone numbers.
This ensures no third party attacks or malicious encounters happen on your app.
One-to-one or Group Messaging: The foremost feature of a chat system design is the ability to send and receive messages. It can be peer-to-peer (1:1) or group chat as per your users requirements.
Push notifications: Don’t let your users miss out on any incoming message/ reaction. Alert them from time to time on their device’s notification pane, and draw attention and engagement effortlessly.
Personalization and user settings: Everything is customizable these days and chat apps are not an exception. Give your users to leverage creativity and fun in their own style with font colors, themes, background colors, profile photos and more.
Read Receipts: Create a sense of urgency and user retention by showing them that the message they’ve sent to others have been delivered successfully and read by them.
Media Shares: Plain text messages are outdated. Users have moved on to images, audio, video, emojis and gifs for interesting conversations.
This indeed is not over. There are plenty of chat features that you can consider adding to your app for building modern messaging experiences!
So, you now know what features to add when planning the dev process of your chat application and its system design, but which framework and technology should you build them on?
Let’s get into the details now!
Backend Programming Languages:
There are plenty of programming languages out there to build a messaging app. But you’ll need to find which one of them is right for the front-end and back-end of your app’s use case.
Here is a list of the best backend programming languages that can be used to build a chat infrastructure.
Backend Programming Languages:
Languages | Pros | Best for |
Erlang | Concurrency, scalability, and reliability | Large-scale messaging apps |
Scala | Scalability and multi-threaded functionality | Social media and messaging apps |
PHP | Great for web applications | Websites and small-scale messaging apps |
Java | Popularity and versatility | Enterprise-level messaging apps |
JavaScript (Node.js) | Front-end and back-end can be written in the same language | Cross-platform and real-time messaging apps |
Frontend Programming Languages:
Languages | Pros of the Language | Best for (Industries Served) |
JavaScript | Easy to learn, versatile, cross-platform compatibility | All types of industries, web-based chat applications |
Swift | Provides a native iOS feel, fast and powerful | iOS-based chat applications |
Kotlin/Java | Provides a native Android feel, fast and efficient | Android-based chat applications |
Messaging App Frameworks
Many frameworks and tools are available that are designed to incorporate chat functionality into new and existing applications. Choosing which frameworks to use when making a messaging app should not be taken lightly, as this decision can either save or cost you hundreds of developer hours.
When you build chat functionality into your new or existing apps, you can choose any framework or tool from hundreds of options available in the market. However, you need to put some serious focus on choosing the right framework for your app, as it highly impacts the cost and time of your app development.
Here are a few of the components you must carefully choose:
Chat Protocols
A chat protocol is a set of rules that will define how your messaging app installed on different user devices will communicate with each other. These protocols enable different messaging apps to exchange data and messages seamlessly. Some of the popular chat protocols used in messaging apps include:
XMPP (Extensible Messaging and Presence Protocol): It is an open-source protocol used for instant messaging and presence information. XMPP is highly extensible and supports a range of features, including group chats, voice and video calls, and file transfers.
MQTT (Message Queuing Telemetry Transport): MQTT is a lightweight protocol used for the Internet of Things (IoT) and real-time communication. It is designed to be highly efficient and supports both push and pull messaging models.
WebRTC (Web Real-Time Communication): WebRTC is an open-source protocol used for real-time audio and video communication over the Internet. It provides a range of features, including video and audio calling, screen sharing, and file transfer.
Chat SDK
A Chat SDK (Software Development Kit) is a pre-built set of tools and libraries that help developers integrate chat features into their applications. The SDK includes everything from messaging interfaces to server-side APIs that handle chat exchange between users, real-time notifications, and more.
MirrorFly Chat SDK: The Best Option To Build Messaging Apps
MirrorFly is a leading in-app communication provider that offers a wide range of features and functionalities via its chat SDK. It includes chat APIs for instant messaging, audio, and video calls, real-time presence indicators, read receipts, and file sharing. The SDK is highly scalable, making it an ideal choice for apps with high user traffic. It supports multiple chat protocols, including XMPP, MQTT, and WebSockets, making it compatible with a wide range of messaging apps.
In addition, MirrorFly Chat SDK is available as a SaaS product for a recurring monthly subscription and as a self-hosted chat solution for a one-time license cost. Here are a few of the perks of the SDK you must never miss out on when designing a chat application!
MirrorFly Cloud Solution (SaaS)
- Free chat solution provider
- Lets you host your chat app on a dedicated cloud server
- Offers 21-day FREE trial of voice and video call SDKs
- Supports multi-tenancy
MirrorFly Self-hosted Chat Solution (SaaP)
- Provides 100% customizable video, voice, and chat SDKs
- You can avail lifetime access to features for a one-time license cost
- Lets you conveniently host your app on-premise
- Offers white-label solution
So why wait, get started with the #1 Chat solution and build the most competitive chat app and its system design!
Conclusion
In conclusion, designing a chat app architecture can sometimes be a daunting task, but with the right frameworks and protocols, the development becomes much easier. In addition to this, pre-built UI kits with SDKs like MirrorFly make building a chat app easy and effortless.
If you are just getting started, MirrorFly’s Free chat SDK can be a good place to start with!
And now, I’ll bid my bye and get back with yet another interesting article soon. Until then, post in your comments and queries about designing a chat system below, and our team of experts will be happy to help you anytime!