18 Websocket Fastapi

title: WebSocket Support in FastAPI REST APIs weight: 28 date: 2026-06-28 lastmod: 2026-06-28 description: Implement WebSocket connections in FastAPI for real-time bidirectional communication including chat, notifications, and live data streaming with connection management. tags: [api-development, fastapi]

FastAPI WebSocket support enables real-time bidirectional communication using the WebSocket protocol, with automatic upgrade handling, message broadcasting, connection lifecycle management, and integration with existing authentication.

```python
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from typing import Set

app = FastAPI()

class ConnectionManager:
    def __init__(self):
        self.active_connections: Set[WebSocket] = set()

    async def connect(self, websocket: WebSocket):
        await websocket.accept()
        self.active_connections.add(websocket)

    def disconnect(self, websocket: WebSocket):
        self.active_connections.discard(websocket)

    async def broadcast(self, message: str):
        for connection in self.active_connections:
            try:
                await connection.send_text(message)
            except WebSocketDisconnect:
                self.disconnect(connection)

manager = ConnectionManager()

@app.websocket("/ws/chat")
async def websocket_endpoint(websocket: WebSocket):
    await manager.connect(websocket)
    try:
        while True:
            data = await websocket.receive_text()
            await manager.broadcast(f"User: {data}")
    except WebSocketDisconnect:
        manager.disconnect(websocket)
        await manager.broadcast("A user disconnected")

What's Next

Now learn about background tasks in Building REST APIs with FastAPI.