MQTT Hex Decoder

MQTT is a lightweight publish-subscribe messaging protocol widely used in IoT telemetry and command channels over constrained networks.

Decode MQTT Data

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Raw Decode Output

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Decoded Fields

Payload Hex: N/A

Payload ASCII: N/A

Additional Insights

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About MQTT

MQTT packets begin with a compact fixed header that identifies packet type and payload size. This quick decode helps classify broker/client traffic like CONNECT, PUBLISH, SUBSCRIBE, and ACK flows.

MQTT is a lightweight publish-subscribe messaging protocol widely used in IoT telemetry and command channels over constrained networks.

MQTT Header Structure

Byte 1: control packet type (upper nibble) and packet flags (lower nibble).
Remaining Length: variable-length integer encoding payload size after fixed header.
Variable header + payload: packet-type-specific fields such as topic, QoS metadata, and message body.

Why Decode MQTT Packets

Decode MQTT fixed header fields from hex including control packet type, flags, and remaining length.