Connect Python to an MQTT broker with paho-mqtt. Start on the free public broker, then point the same code at a secure private broker on ConnectMQ.
mqtt-code-samples/pythonClone the complete, runnable examples. Stars and pull requests welcome. View on GitHub No account needed: connect to broker.connectmq.com on port 1883 and start publishing in seconds.
import json
import paho.mqtt.client as mqtt
TOPIC = "your-project/sensors/temperature" # Use a unique topic prefix: everyone can read the public broker
# Runs when the connection is established
def on_connect(client, userdata, flags, reason_code, properties):
print("Connected:", reason_code)
# Subscribe to the temperature topic
client.subscribe(TOPIC, qos=1)
# Publish a JSON reading
client.publish(TOPIC, json.dumps({"temperature": 21.5}), qos=1)
# Runs for every message on a subscribed topic
def on_message(client, userdata, msg):
print(msg.topic, msg.payload.decode())
client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
client.on_connect = on_connect
client.on_message = on_message
# Connect to the free public broker (no account needed)
client.connect("broker.connectmq.com", 1883)
# Keep the client running
client.loop_forever()
The public broker is shared: anyone can subscribe to your topics. Never send passwords, personal data or anything confidential through it.
About the free public MQTT brokerFor real devices, use a private serverless MQTT broker on ConnectMQ instead of the public one: TLS encryption, a username and password for every device and per-topic access control, fully managed. Start on the Free plan — no card required.
Replace YOUR_BROKER_HOST, YOUR_USERNAME and YOUR_PASSWORD with the values from your ConnectMQ dashboard.
import json
import paho.mqtt.client as mqtt
TOPIC = "your-project/sensors/temperature"
# Runs when the connection is established
def on_connect(client, userdata, flags, reason_code, properties):
print("Connected:", reason_code)
# Subscribe to the temperature topic
client.subscribe(TOPIC, qos=1)
# Publish a JSON reading
client.publish(TOPIC, json.dumps({"temperature": 21.5}), qos=1)
# Runs for every message on a subscribed topic
def on_message(client, userdata, msg):
print(msg.topic, msg.payload.decode())
client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
client.on_connect = on_connect
client.on_message = on_message
# Username and password from your ConnectMQ dashboard
client.username_pw_set("YOUR_USERNAME", "YOUR_PASSWORD")
# TLS: the system CA store verifies the broker certificate
client.tls_set()
# Connect to your private ConnectMQ broker on port 8883
client.connect("YOUR_BROKER_HOST", 8883)
# Keep the client running
client.loop_forever()
Install paho-mqtt 2.x, connect to the broker host on port 1883 (or 8883 with TLS), then subscribe to a topic and publish messages to it. The examples on this page connect to the free public broker broker.connectmq.com and to a private ConnectMQ broker.
Yes. broker.connectmq.com is a free public MQTT broker that needs no account. Anyone can read its topics, so use it only for tests and use a unique topic prefix.
Connect over TLS on port 8883 with a username and password from your ConnectMQ dashboard, and give every device its own credentials and topic permissions instead of using the public broker.
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View exampleTest any example on broker.connectmq.com — no sign-up, MQTT 3.1.1 and 5, TCP, TLS and WebSocket.
About the free public MQTT brokerWhen it is time for real devices, run the same code on a private, fully managed ConnectMQ broker with TLS and per-device credentials.
Start for freeCreate an account, get your broker credentials and connect your first device — no servers to install, patch or scale.
