Presence Detection

Real-Time Presence

Know who is online, who is typing, who just left. Built on MQTT's native presence capabilities.

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Presence Without the Plumbing

MQTT was designed for presence from day one. Last Will messages, retained state, and QoS delivery make it the ideal protocol.

Online/Offline Detection

Know instantly when users connect or disconnect. Retained messages store last-known state for late joiners.

Typing Indicators

Lightweight typing events over dedicated topics. Sub-100ms delivery for responsive chat experiences.

Last Will & Testament

MQTT's native LWT feature automatically publishes an offline message when a client disconnects unexpectedly.

Automatic Cleanup

Session tracking with automatic state cleanup. No stale presence data, no ghost users in your UI.

Last Will & Testament

Automatic Disconnect Detection

Set an online status on connect and a Last Will message for disconnect. The broker handles the rest — even if the client crashes or loses network.

Retained State
Presence messages are retained so new subscribers get current state immediately
QoS 1 Delivery
At-least-once delivery guarantees no missed presence updates
Topic-Based Channels
Organize presence by room, team, or application with topic hierarchies
Delivery Metrics
Track presence delivery rates and session durations in the dashboard
presence.js
// Publish presence on connect
client.publish('presence/alice',
JSON.stringify({
status: 'online',
timestamp: Date.now()
}), { retain: true, qos: 1 }
)
// Set last will for disconnect
client.connect({
will: {
topic: 'presence/alice',
payload: '{"status":"offline"}',
retain: true, qos: 1
}
})

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Add real-time presence to your app with MQTT topics and retained messages. Free tier included.

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