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Public MQTT broker

Free public MQTT broker

A free, shared MQTT broker for learning, prototyping and testing. Connect any MQTT 3.1.1 or MQTT 5 client and start publishing in seconds.

Broker addressbroker.connectmq.com
  • MQTT 3.1.1 and MQTT 5
  • TCP, TLS, WebSocket and secure WebSocket
  • Works with any MQTT client
Connect

Connection details

Use the port that matches your client. Browsers need WebSocket; prefer the encrypted ports whenever your client supports them.

ProtocolPortAddressDescription
MQTT1883mqtt://broker.connectmq.com:1883Unencrypted TCP
MQTT over TLS8883mqtts://broker.connectmq.com:8883TLS-encrypted TCP
WebSocket8083ws://broker.connectmq.com:8083/mqttWebSocket, path /mqtt
Secure WebSocket8084wss://broker.connectmq.com:8084/mqttSecure WebSocket, path /mqtt

Before you use the public broker

  • It is public and shared: anyone can subscribe to any topic, including yours.
  • Never send passwords, personal data or anything confidential.
  • Use a unique topic prefix (for example your-project/…) so your messages do not mix with others.
  • There is no guarantee of availability or message retention, and abusive traffic may be blocked.
  • For real devices and production data, use a private ConnectMQ broker.
Try it

Your first message in two commands

With the mosquitto command-line tools installed, subscribe in one terminal and publish from another.

Code samples for Python, Node.js, browsers, ESP32 and Go

Subscribe
mosquitto_sub -h broker.connectmq.com -p 1883 -t "your-project/#" -v
Publish
mosquitto_pub -h broker.connectmq.com -p 1883 -t "your-project/hello" -m "Hello from ConnectMQ"
Going to production

From the public broker to your own

Public broker

  • Free and shared with everyone
  • No authentication or access control
  • No guarantees — for learning and tests

Private ConnectMQ broker

  • Isolated broker for your devices only
  • TLS, username/password and per-topic access control
  • Dashboard, rules, alerts and Digital Twin
Get started See pricing

Public broker FAQ

Is the public MQTT broker free?

Yes. The public broker at broker.connectmq.com is free to use for learning, prototyping and testing.

Is it secure to use?

Traffic on the TLS and secure WebSocket ports is encrypted, but the broker itself is public: anyone can subscribe to your topics. Do not send sensitive data through it.

Which MQTT versions are supported?

MQTT 3.1.1 and MQTT 5, over TCP (1883), TLS (8883), WebSocket (8083) and secure WebSocket (8084), both WebSocket ports with the path /mqtt.

Can I use it in production?

No. The public broker has no access control and no guarantees. For real devices, create a private ConnectMQ broker — start on the Free plan with no card.

Ready for your own private broker?

Create an account, get your broker credentials and connect your first device — no servers to install, patch or scale.

Get started See pricing

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