Connect Go to an MQTT broker with the Eclipse Paho Go client. Start on the free public broker, then point the same code at a secure private broker on ConnectMQ.
mqtt-code-samples/goClone 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.
package main
import (
"fmt"
"time"
mqtt "github.com/eclipse/paho.mqtt.golang"
)
func main() {
topic := "your-project/sensors/temperature" // Use a unique topic prefix: everyone can read the public broker
// Connect to the free public broker (no account needed)
opts := mqtt.NewClientOptions().AddBroker("tcp://broker.connectmq.com:1883")
// Every client needs a unique client ID
opts.SetClientID(fmt.Sprintf("go-%d", time.Now().UnixNano()))
// Reconnect automatically if the connection drops
opts.SetAutoReconnect(true)
// Runs when the connection is established
opts.SetOnConnectHandler(func(c mqtt.Client) {
// Subscribe to the temperature topic
c.Subscribe(topic, 1, func(_ mqtt.Client, m mqtt.Message) {
fmt.Printf("%s: %s\n", m.Topic(), m.Payload())
})
})
client := mqtt.NewClient(opts)
if t := client.Connect(); t.Wait() && t.Error() != nil {
panic(t.Error())
}
// Publish a JSON reading
client.Publish(topic, 1, false, `{"temperature":21.5}`).Wait()
// Keep the client running
select {}
}
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.
package main
import (
"crypto/tls"
"fmt"
"time"
mqtt "github.com/eclipse/paho.mqtt.golang"
)
func main() {
topic := "your-project/sensors/temperature"
// Connect to your private ConnectMQ broker on port 8883
opts := mqtt.NewClientOptions().AddBroker("ssl://YOUR_BROKER_HOST:8883")
// Username and password from your ConnectMQ dashboard
opts.SetUsername("YOUR_USERNAME")
opts.SetPassword("YOUR_PASSWORD")
// TLS: the system CA store verifies the broker certificate
opts.SetTLSConfig(&tls.Config{MinVersion: tls.VersionTLS12})
// Every client needs a unique client ID
opts.SetClientID(fmt.Sprintf("go-%d", time.Now().UnixNano()))
// Reconnect automatically if the connection drops
opts.SetAutoReconnect(true)
// Runs when the connection is established
opts.SetOnConnectHandler(func(c mqtt.Client) {
// Subscribe to the temperature topic
c.Subscribe(topic, 1, func(_ mqtt.Client, m mqtt.Message) {
fmt.Printf("%s: %s\n", m.Topic(), m.Payload())
})
})
client := mqtt.NewClient(opts)
if t := client.Connect(); t.Wait() && t.Error() != nil {
panic(t.Error())
}
// Publish a JSON reading
client.Publish(topic, 1, false, `{"temperature":21.5}`).Wait()
// Keep the client running
select {}
}
Install Eclipse Paho Go, 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 exampleConnect Node-RED to an MQTT broker with an importable flow.
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.
