Real-Time Chat App Using Flask and Socket.IO Step-by-Step

This chat app will let users:

• Join a chatroom 
• Send/receive messages in real-time 
• See who joined or left 

We’ll build it step-by-step, no skips. Let’s start.

🔧 Step 1: Setup Your Environment

✅ 1.1. Create a project folder

Bash: mkdir flask-chat-app

cd flask-chat-app

 

✅ 1.2. Create a virtual environment (optional but recommended)

Bash: python -m venv venv

source venv/bin/activate  # On Windows: venv\Scripts\activate

 

✅ 1.3. Install dependencies

Bash: pip install flask flask-socketio eventlet

 

📁 Step 2: Project Structure

flask-chat-app/

│

├── app.py                 ← Main Flask server

├── templates/

│   └── index.html         ← Chat page UI

├── static/

│   └── chat.js            ← Client-side JS for real-time messaging

▶️ Step 6: Run the App

 

Bash: python app.py

 

Then visit:

http://localhost:5000

🧪 Try It Out

• Open the app in two browser windows/tabs. 
• Type a message in one window — it shows instantly in both! 

✅ You Now Have:

• Flask server with WebSocket support 
• Real-time 2-way messaging using Socket.IO 
• Dynamic UI for chatting 

🛠️ Next Steps (Optional Add-ons)

Let me know if you want to add:

• Usernames 
• Rooms 
• Timestamps 
• Join/leave notifications 
• Message persistence (SQLite or Firebase) 
• Emojis or themes 

I’ll walk you through each!

👤 Step-by-Step: Add Usernames to the Chat App

🧠 New Behavior:

• When a user opens the chat, they’ll be asked to enter a username. 
• Their username will appear next to every message. 
• Everyone will see when a user joins or leaves.