Pub/Sub Messaging Built on MQTT 5.0
The publish/subscribe pattern at scale. Route messages to the right clients instantly, with delivery guarantees and persistent sessions built into the protocol.
How Pub/Sub Works
Publishers and subscribers never communicate directly. The broker handles routing, so each side can scale independently.
Any client that sends a message to a topic. It has no knowledge of who is listening.
Any client that declares interest in a topic. It has no knowledge of who is publishing.
Publishers and subscribers are fully decoupled — they can come and go independently. The broker handles fan-out, queuing, and session state.
Protocol Capabilities
MQTT 5.0 was designed for exactly these problems. Every capability below is native to the protocol — not bolted on.
QoS Levels
Choose your delivery guarantee. QoS 0 for fire-and-forget speed, QoS 1 for at-least-once delivery, QoS 2 for exactly-once semantics.
Retained Messages
The broker stores the last message on any topic. New subscribers instantly receive the current state without waiting for the next publish.
Topic Wildcards
Use + to match a single level (devices/+/status) and # to match multiple levels (sensors/#). Build flexible subscriptions with minimal rules.
Offline Queuing
Messages are stored while a client is disconnected and delivered the moment it reconnects. No data loss for intermittent connections.
Persistent Sessions
The broker remembers a client's subscriptions across disconnects. Clients resume exactly where they left off without re-subscribing.
Last Will & Testament
Register a message to be published automatically when a client disconnects unexpectedly. Presence detection built into the protocol.
Why Not HTTP or WebSockets?
HTTP polling and raw WebSockets leave critical messaging primitives up to your application code. MQTT provides them at the protocol layer.
| Feature | HTTP | WebSocket | MQTT |
|---|---|---|---|
| Real-time push | |||
| Pub/Sub routing | |||
| Delivery guarantees (QoS) | |||
| Offline message queuing | |||
| Persistent sessions | |||
| Retained messages | |||
| Last Will & Testament | |||
| Topic-based ACL | |||
| Low overhead (binary protocol) | |||
| Works over plain HTTP |
Topic Architecture
Topics are hierarchical paths that define message routing. Design your namespace once and it scales across every use case.
Each user subscribes to their own topic. Only they receive their messages.
All members subscribe to the same room topic and see every post.
Sensors publish readings; dashboards subscribe to selected devices.
Route tasks and responses directly to individual agent instances.
Start Building with Pub/Sub
Connect your first client in minutes. Free tier includes 5,000 messages per day with no credit card required.