Hi Product Hunt! 👋

I'm Josh, hunter of TestMQTT.

The problem
Every time I wanted to check whether an MQTT broker was alive, whether my credentials worked or what a device was actually publishing, I had to install a desktop client or remember mosquitto_sub flags. Sharing a quick test with a teammate meant sending screenshots.

What TestMQTT does
It's a complete MQTT test client in a browser tab. Open the page, pick a broker and you're connected. No install, no account. Your MQTT username, password and message contents are never stored.

✅ Connect to any broker over WebSockets (ws:// / wss://) with username, password, client ID, keep-alive and Last Will
✅ MQTT 3.1.1 & 5, QoS 0/1/2, retained messages, + and # wildcards
🌳 Live topic tree with message counts
🔍 Payload inspector that detects JSON, numbers, text and binary, with a sparkline for numeric topics
🧹 One-click "clear retained message"
🔗 Shareable deep links to a broker + topic, handy for debugging with your team
🧰 Free tools: code generator (Python, JS, Node.js, ESP32/Arduino, Go, Mosquitto CLI), mosquitto.conf generator, reason code lookup, wildcard tester, packet size calculator, client ID generator
📚 Learn MQTT guides (ports, QoS, connection errors, public vs. private brokers)
🌍 Available in English, Spanish, Portuguese, German, French and Turkish

Public test brokers from ConnectMQ, HiveMQ, EMQX, Eclipse Mosquitto and Eclipse Projects are one click away.

One limitation: browsers can't open raw TCP sockets, so TestMQTT connects over WebSockets only. Most brokers support this on ports like 8083/8084.

Thanks for checking it out! 🙏

Hi Product Hunt! 👋

I'm Josh, hunter of TestMQTT.

The problem
Every time I wanted to check whether an MQTT broker was alive, whether my credentials worked or what a device was actually publishing, I had to install a desktop client or remember mosquitto_sub flags. Sharing a quick test with a teammate meant sending screenshots.

What TestMQTT does
It's a complete MQTT test client in a browser tab. Open the page, pick a broker and you're connected. No install, no account. Your MQTT username, password and message contents are never stored.

✅ Connect to any broker over WebSockets (ws:// / wss://) with username, password, client ID, keep-alive and Last Will
✅ MQTT 3.1.1 & 5, QoS 0/1/2, retained messages, + and # wildcards
🌳 Live topic tree with message counts
🔍 Payload inspector that detects JSON, numbers, text and binary, with a sparkline for numeric topics
🧹 One-click "clear retained message"
🔗 Shareable deep links to a broker + topic, handy for debugging with your team
🧰 Free tools: code generator (Python, JS, Node.js, ESP32/Arduino, Go, Mosquitto CLI), mosquitto.conf generator, reason code lookup, wildcard tester, packet size calculator, client ID generator
📚 Learn MQTT guides (ports, QoS, connection errors, public vs. private brokers)
🌍 Available in English, Spanish, Portuguese, German, French and Turkish

Public test brokers from ConnectMQ, HiveMQ, EMQX, Eclipse Mosquitto and Eclipse Projects are one click away.

One limitation: browsers can't open raw TCP sockets, so TestMQTT connects over WebSockets only. Most brokers support this on ports like 8083/8084.

Thanks for checking it out! 🙏

TestMQTT

Test any MQTT broker from your browser, no install

Test any MQTT broker from your browser, no install