Need help with Flask-MQTT?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

154 Stars 49 Forks MIT License 196 Commits 20 Opened issues


Flask Extension for the MQTT protocol

Services available


Need anything else?

Contributors list


Flask Extension for the MQTT protocol. Basically it is a thin wrapper around paho-mqtt and aims to simplify MQTT integration in Flask. MQTT is a machine-to-machine "Internet of Things" protocol and was designed for extremely lightweight publish/subscribe messaging transport.

Documentation Status PyPI version Travis CI Coverage Status Anaconda-Server Badge Downloads Downloads

Find the documentation on


  • configuration via Flask config variables
  • auto-connect on start of your web application
  • publish and subscribe messages
  • use callbacks for certain topics
  • use one callback for all subscribed topics


Flask-MQTT was developed to provide an easy-to-setup solution for interacting with IoT devices. A typical scenario would be a Raspberry Pi running a mosquitto mqtt server combined with a Flask webserver.

Multiple workers

Flask-MQTT is currently not suitable for the use with multiple worker instances. So if you use a WSGI server like gevent or gunicorn make sure you only have one worker instance.


Make sure to disable Flasks autoreloader. If activated it spawns two instances of a Flask application. This leads to the same problems as multiple workers. To prevent Flask-MQTT from running code twice it is necessary to deactivate the automatic reloader.


Simply install the package as usual via pip:

$ pip install flask-mqtt

Or with conda from the conda-forge channel:

$ conda config --add channels conda-forge
$ conda install flask-mqtt


Basic Setup

from flask import Flask
from flask_mqtt import Mqtt

app = Flask(name) app.config['MQTT_BROKER_URL'] = '' app.config['MQTT_BROKER_PORT'] = 1883 app.config['MQTT_USERNAME'] = 'user' app.config['MQTT_PASSWORD'] = 'secret' app.config['MQTT_REFRESH_TIME'] = 1.0 # refresh time in seconds mqtt = Mqtt(app)

@app.route('/') def index(): return render_template('index.html')

Subscribe to a topic

To subscribe to a topic simply use

. To make sure the subscription gets handled correctly on startup place the subscription inside an
callback function.
def handle_connect(client, userdata, flags, rc):

To handle the subscribed messages you can define a handling function by decorating it with

def handle_mqtt_message(client, userdata, message):
    data = dict(

To unsubscribe do:


Or if you want to unsubscribe all topics use



To publish a message you can use the

mqtt.publish('home/mytopic', 'this is my message')

Small publish/subscribe MQTT client


A small Test application to show how to use Flask-MQTT.


import eventlet import json from flask import Flask, render_template from flask_mqtt import Mqtt from flask_socketio import SocketIO from flask_bootstrap import Bootstrap


app = Flask(name) app.config['SECRET'] = 'my secret key' app.config['TEMPLATES_AUTO_RELOAD'] = True app.config['MQTT_BROKER_URL'] = '' app.config['MQTT_BROKER_PORT'] = 1883 app.config['MQTT_USERNAME'] = '' app.config['MQTT_PASSWORD'] = '' app.config['MQTT_KEEPALIVE'] = 5 app.config['MQTT_TLS_ENABLED'] = False app.config['MQTT_CLEAN_SESSION'] = True

Parameters for SSL enabled

app.config['MQTT_BROKER_PORT'] = 8883

app.config['MQTT_TLS_ENABLED'] = True

app.config['MQTT_TLS_INSECURE'] = True

app.config['MQTT_TLS_CA_CERTS'] = 'ca.crt'

mqtt = Mqtt(app) socketio = SocketIO(app) bootstrap = Bootstrap(app)

@app.route('/') def index(): return render_template('index.html')

@socketio.on('publish') def handle_publish(json_str): data = json.loads(json_str) mqtt.publish(data['topic'], data['message'])

@socketio.on('subscribe') def handle_subscribe(json_str): data = json.loads(json_str) mqtt.subscribe(data['topic'])

@socketio.on('unsubscribe_all') def handle_unsubscribe_all(): mqtt.unsubscribe_all()

@mqtt.on_message() def handle_mqtt_message(client, userdata, message): data = dict( topic=message.topic, payload=message.payload.decode() ) socketio.emit('mqtt_message', data=data)

@mqtt.on_log() def handle_logging(client, userdata, level, buf): print(level, buf)

if name == 'main': # important: Do not use reloader because this will create two Flask instances. # Flask-MQTT only supports running with one instance, host='', port=5000, use_reloader=False, debug=False)

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.