🔌 Build a Real-Time Chat App using Flutter & FastAPI with WebSockets
📅 Published by TechyCodex.com | ✍️ Written by Parikshit Verma
Learn how to create a simple real-time chat app using WebSockets — Flutter for frontend and FastAPI for backend!
🔍 Why This Project?
If you’re just starting with real-time apps or trying to understand WebSockets, this tutorial will guide you with a clean, beginner-friendly project.
You’ll learn:
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📲 How to send/receive messages in real-time using WebSockets
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⚙️ How Flutter connects to a FastAPI backend using web_socket_channel
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💡 How real-time systems work behind the scenes
This is a great starting point to learn the basics of WebSocket protocol using modern tech.
🛠️ Tech Stack
Frontend: Flutter(Dart)
Backend: FastApi(Python)
Communication: WebSocket Protocol
⚡ What Are WebSockets?
WebSockets allow for full-duplex communication between client and server — unlike HTTP, which is request-response based.
In this app:
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The Flutter app connects to the FastAPI server via WebSocket.
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When a user sends a message, it's broadcast to all connected clients instantly.
📱 Flutter UI Highlights
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The app starts with a screen to enter your username.
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Once entered, you're taken to the chat screen.
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Messages are shown with:
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✉️ Sender Name
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💬 Message Content
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🕒 Timestamp
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Messages sent by you are aligned right, others to the left.
🧠 Backend Logic (FastAPI + WebSocket)
Here's how the backend works:
@app.websocket("/ws") async def websocket_endpoint(websocket: WebSocket): await websocket.accept() clients.append(websocket) try: while True: data = await websocket.receive_text() for client in clients: await client.send_text(data) except: clients.remove(websocket)
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Clients are appended to a clients[] list
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On receiving a message, it is broadcasted to everyone
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If a user disconnects, they're removed
🔥 That’s the power of WebSockets — simple, lightweight, real-time!
🔗 Source Code (GitHub)
👉 GitHub Repository – Flutter + FastAPI WebSocket Chat App
📦 How to Run It?
🚀 Backend (Python + FastAPI)
cd server pip install fastapi uvicorn uvicorn main:app --reload --host 0.0.0.0 --port 8080
📱 Frontend (Flutter)
cd flutter_app flutter pub get flutter run
📌 Make sure both your devices (or emulator) and server are on the same network.
🧪 Sample Chat Flow
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Enter your name
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Chat window opens
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Message sent → Received by all users in real time!
📌 Ideal For:
✅ College projects
✅ Real-time systems demo
✅ Learning Flutter state management
✅ Understanding WebSocket lifecycle
💡 Want to Go Further?
You can extend this app with:
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🔐 User authentication (Firebase or JWT)
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💾 Chat history storage (MongoDB, SQLite)
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📲 Web version using Flutter Web
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🧑🤝🧑 Group chats and private rooms
📚 Final Thoughts
This project was built with one goal in mind — learn WebSockets practically.
No fancy setup, no overwhelming dependencies — just clean logic and real-time magic.
If you’re looking to get started with real-time apps, this is your launchpad. 🚀
🔗 GitHub
👉 TechyCodex WebSocket Chat App Source Code
🔥 Keywords for SEO
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WebSocket with Flutter and FastAPI
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Real-time chat app in Flutter
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FastAPI WebSocket tutorial
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Flutter socket connection
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Build chat app using WebSocket
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Flutter + FastAPI full-stack
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