Flask-SocketIO is an extension for Flask that allows real-time, bidirectional communication between the server and clients using WebSockets. In this guide, we'll build a simple chat application with Flask-SocketIO. Users will be able to send and receive messages in real-time, creating a dynamic and interactive chat experience. By following this guide, you'll gain an understanding of how to implement real-time communication with Flask-SocketIO in a chat application.

Step 1: Setting Up Your Flask Application

Start by setting up your Flask application and creating a directory structure. Here's a sample structure:


Step 2: Installing Flask and Flask-SocketIO

Install Flask and Flask-SocketIO using pip:

pip install Flask
pip install Flask-SocketIO

Step 3: Creating the Flask Application

Create your Flask application. Here's an example of Python code:

from flask import Flask, render_template
from flask_socketio import SocketIO, emit
app = Flask(__name__)
app.config['SECRET_KEY'] = 'your_secret_key'
socketio = SocketIO(app)
def index():
return render_template('chat.html')
def handle_message(message):
emit('message', message, broadcast=True)
if __name__ == '__main__':, debug=True)

Step 4: Creating the HTML Template

Create an HTML template for your chat application. Here's an example of the chat template:

<!-- templates/chat.html -->
<!DOCTYPE html>
<title>Chat Application</title>
<h1>Chat Application</h1>
<div id="message-container">
<ul id="message-list"></ul>
<input id="message-input" type="text" placeholder="Type your message">
<button id="send-button">Send</button>
<script src=""></script>
var socket = io.connect('http://' + document.domain + ':' + location.port);
socket.on('message', function(message) {
var messageList = document.getElementById('message-list');
var li = document.createElement('li');
li.innerHTML = message;
document.getElementById('send-button').onclick = function() {
var messageInput = document.getElementById('message-input');
var message = messageInput.value;
socket.emit('message', message);
messageInput.value = '';


Building a chat application with Flask-SocketIO allows you to create a real-time communication platform. By following this guide, you've learned how to set up your Flask application, configure Flask-SocketIO, and create the chat interface. Users can send and receive messages in real-time. You can extend this foundation to add user authentication, private messaging, and more features to your chat application.