---
id: flask-socketio
version: "5.6.1"
license: unclear
license_treatment: permissive
maintenance: active
---

# Flask-SocketIO — Socket.IO integration for Flask applications

License: permissive · Maintenance: active · Downloads: 5.2M/mo

## What it is and what it does

Flask-SocketIO bridges Flask applications with Socket.IO, a library that enables real-time, event-driven communication between server and client over WebSockets. It wraps the python-socketio package and integrates it into Flask's request/response model, letting you define event handlers as decorators and emit messages bidirectionally. The package depends on flask, python-socketio, werkzeug, jinja2, click, and blinker—all standard Flask ecosystem components.

Typical use is defining server-side event handlers with @socketio.event decorators, then running the app with socketio.run() instead of app.run(). Clients connect via a JavaScript Socket.IO client library and exchange JSON-serializable messages. This pattern is common for live dashboards, collaborative tools, notifications, and any application where the server needs to push updates to connected clients without polling.

Use it for:

- Build live notification systems where the server pushes alerts to connected browsers in real time.
- Create collaborative editing or whiteboarding applications with instant synchronization across clients.
- Implement live dashboards and monitoring interfaces that update without page refresh.
- Add real-time chat or messaging features to Flask web applications.
- Stream live data (stock prices, sensor readings, game state) to multiple clients simultaneously.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Flask-SocketIO adds real-time bidirectional communication to Flask applications using WebSockets, allowing servers and clients to emit and receive events instantly.

Yes. Flask-SocketIO is actively maintained, has low install friction, carries a permissive MIT license, and solves a real problem—adding WebSocket support to Flask with minimal boilerplate. It's in the top 5000 packages by downloads and has no known vulnerabilities. Install it if you need real-time bidirectional communication in a Flask app.

## Install

pip install flask-socketio
uv add flask-socketio
poetry add flask-socketio

## Installing Flask-SocketIO

Before you install: Low friction install with a pure-Python wheel. Actively maintained with recent releases; last commit 2026-07-30 and 5508 repository stars indicate ongoing support.

License in practice: MIT license (permissive) means you can use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.

Quickstart:

pip install flask-socketio

from flask import Flask
from flask_socketio import SocketIO, emit

app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)

@socketio.event
def my_event(message):
    emit('my_response', {'data': 'got it!'})

if __name__ == '__main__':
    socketio.run(app)

Requires Python 3.8 or later; production deployment typically needs a production WSGI server and may require additional configuration for WebSocket support.

Verify before relying:

- Whether the package handles reconnection and fallback transports automatically or requires manual configuration.
- Performance characteristics and scalability limits for concurrent connections.
- Specific deployment requirements beyond standard Flask WSGI servers.

## Package facts

- License: not declared (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 5.2M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

websocket flask, real-time communication python, socket.io flask integration, bidirectional messaging web, live event streaming flask, websocket server python, flask real-time events, websocket, real-time, event-driven

[View on SkillFed](https://skillfed.io/packages/flask-socketio) · [View on PyPI](https://pypi.org/project/flask-socketio/)