Plaintext TCP
Default port 1883. Fastest to set up on a trusted network, but nothing is encrypted — the app warns before you save a plaintext broker.
MQTT for Mac
Turn MQTT messages into native Mac notifications.
NTBX subscribes to your broker and delivers each MQTT message to the Mac menu bar and Notification Center — titles, topics and payloads, in a searchable local inbox. No scripts, no dashboard to keep open.
mqtt:// · mqtts:// · ws:// · wss://
MQTT 3.1.1
WebSocket brokers
QoS 0 & 1
Free on the Mac App Store · macOS 14 or later
Quick start
From a broker to Notification Center.
Keep publishing to the broker you already run. NTBX takes care of the subscription, the session, and native delivery on your Mac.
Add the broker
Enter the broker URL, for example
mqtts://broker.example.comorwss://broker.example.com/mqtt, then the topic filter you want to follow.Pick a topic filter
Use
+for one level and#for the rest, such asalerts/#. Choose QoS 1 if you cannot miss a message, QoS 0 if you prefer the lightest connection.Publish something
Send a message from any client. It appears in the NTBX inbox and in macOS Notification Center, with the topic as the subtitle.
mosquitto_pub \
-h broker.example.com -p 8883 \
-t alerts/disk \
-m 'Disk almost full on mac-studio' \
-q 1Add --username and --pw for a broker that requires authentication. NTBX authenticates the same way and stores the password in macOS Keychain.
Transports
MQTT 3.1.1 over WebSocket
A plain TCP broker and a WebSocket broker are both first-class in NTBX. WebSocket support matters when the broker sits behind a web host, where port 1883 is closed and only the web ports are reachable.
TLS over TCP
Default port 8883. Recommended for anything outside your own network. The broker certificate is validated against the macOS trust store.
MQTT over WebSocket
Default ports 80 and 443, with a path such as /mqtt. Use wss:// so the connection stays encrypted; hosts that can only serve HTTP traffic can still deliver MQTT this way.
Subscriptions
Topic filters, QoS, and sessions that resume
+ and # wildcards
alerts/+/disk matches one level, alerts/# matches everything below it. Saved subscriptions keep their filter, so you can follow a whole tree in one place.
QoS 0 and QoS 1
Choose QoS 1 for messages that must arrive once, or QoS 0 for high-volume topics where missing the occasional update is acceptable. Every delivery lands as a desktop notification in Notification Center, with the topic as the subtitle.
Persistent, with a clean reset
NTBX keeps a persistent session keyed by its own Client ID and cleans the broker-side session when the broker, filter, QoS, username or Client ID changes, so no messages arrive twice.
Text, Base64, or skipped
UTF-8 payloads become the notification body. Non-UTF-8 payloads are either skipped or shown as Base64, and oversized publishes are dropped rather than truncated.
Not a debugging client
MQTT Explorer, MQTTAnalyzer and similar tools answer a different question: what is on my broker right now, and how do I publish to it? NTBX answers the one after that — which messages should interrupt me, and where do I find them later. Both can be useful; only one of them belongs in your menu bar all day.
Menu Bar
Live connection status and an unread count, without a window in the way.
Notification Center
Messages arrive as native alerts, with the topic as the subtitle.
Local Inbox
The 20 most recent messages per subscription stay on your Mac and stay searchable.
Keychain
Broker passwords live in macOS Keychain, never in preferences or logs.
Sandboxed
The app runs in the App Sandbox with a hardened runtime and no analytics SDK.
Native Swift
No embedded browser and no background web app — a native Swift client.
A direct connection to your broker.
NTBX connects from your Mac to the broker you configured, with no relay in between. Credentials stay in macOS Keychain, no account is required, and there is no telemetry or third-party tracking SDK.
- Passwords in macOS Keychain
- mqtts:// and wss:// for encrypted brokers
- Retained messages never notify you twice
- User-initiated feedback only
What you need
- System
- macOS 14 Sonoma or later
- Source
- Any MQTT 3.1.1 broker over mqtt://, mqtts://, ws:// or wss://
- Access
- Anonymous or username and password
- History
- Up to 20 recent messages per subscription, stored locally
- Delivery
- NTBX running, Mac awake and online, notifications allowed
Before you connect
MQTT on Mac: practical questions
Which brokers can NTBX connect to?
Any MQTT 3.1.1 broker your Mac can reach: mqtt:// (1883), mqtts:// (8883), ws:// and wss:// (80/443 with a path such as /mqtt). TLS uses the macOS trust store, so the broker certificate has to be valid for the host you enter.
Is QoS 2 supported? What about retained messages?
NTBX subscribes with QoS 0 and QoS 1; QoS 2 is out of scope. Retained messages are deliberately ignored — a retained value is broker state, not a new event, and re-delivering it on every reconnect would produce phantom notifications.
Do I need a public broker to try it?
No. You can point NTBX at a local broker such as mqtt://localhost:1883, and the app's connection test checks the broker and filter before you save. Our App Review broker also sends one demo message to each new session, so you can see delivery without publishing anything.
Will NTBX work with Home Assistant, Zigbee2MQTT or Uptime Kuma?
Yes, as long as the tool publishes to an MQTT broker you can reach. Subscribe to the topic your automation already publishes to; NTBX only reads, it never publishes back.
How do sessions and Client IDs behave?
NTBX uses a stable generated Client ID, or one you set in Advanced (1–23 ASCII alphanumeric characters). Changing the broker, filter, QoS, username or Client ID resets the stored session so the broker starts clean, which prevents both duplicate and stale deliveries.
