Interactive Packet Analyzer

Decode IoT packet bytes into fields, payload, and protocol overhead

Interactive Packet Analyzer

Interactive animation Packet decoding IoT protocols

Interactive Packet Analyzer

Decode real IoT packet bytes into control fields, lengths, identifiers, and payload. Then compare how much of each message is useful data versus protocol overhead.

MQTTSelected protocol

12 bytesTotal packet size

17%Payload efficiency

Goal

See where header bytes end and useful payload bytes begin.

Try

Click a byte or field, then compare MQTT, CoAP, HTTP, and Modbus.

Watch

The highlighted field explains what each byte contributes.

Apply

Use payload efficiency to reason about battery and bandwidth.

Analyzer Setup

Sample Packet MQTT publish MQTT PUBLISH CoAP GET: /temp Modbus read registers HTTP GET: /temp

Compare Payload 2 bytes

Live Numbers

Total

12 B

Payload

2 B

Overhead

10 B

Efficiency

17%

Selected

Control byte

Hex Bytes

30 0A 00...

Packet Field Decoder

The byte strip is the raw packet. Colored groups show which bytes are control, length, identifiers, and payload.

Choose

1. Choose packetSelect a real IoT protocol example.

2. Read fieldsClick bytes to inspect their purpose.

3. Find payloadSeparate useful data from headers.

4. Judge overheadCompare size, transport, and fit.

choose

Packet Fields

Selected Field

Overhead vs Payload

header payload

MQTT keeps this message compact, but the TCP/IP layers below it still add extra bytes on the network.

MQTT PUBLISH 0x30 0x0A carries topic s/temp and payload "25". The remaining length byte is 10, which counts the variable header and payload after the fixed header.

Learning Support

Beginner Model

A packet is a wrapper around data. Header bytes tell the receiver what the data means, where it belongs, and how to process it.

Overhead Rule

Small sensor readings can be only a few bytes. If the header is much larger than the payload, radio time and battery use increase.

What to Notice

• Length fields often count only part of the packet.
• Identifiers connect replies to requests.
• Transport layers add more overhead below this view.

Quick Reference

Protocol	Transport	Minimal App Header	Best Fit	Caution
MQTT	TCP	2 bytes plus topic	cloud pub/sub telemetry	TCP/TLS adds lower-layer overhead
CoAP	UDP	4 bytes plus options	constrained request/response	options still cost bytes
Modbus TCP	TCP	7-byte MBAP plus PDU	industrial register reads	not designed for rich semantic data
HTTP	TCP	text request line plus headers	web APIs and diagnostics	verbose for tiny sensor payloads