Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.6.2, protocol 74) to the current pre-release. Note that this page contains bleeding-edge information that may not be completely or correctly documented. He who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occured to the respective packets there.

Protocol History

13w36a - Added sound category byte to 0x3E - Changed 0xC8 to a string:int map

13w37b -

1.6.3 - Terrain fixes to help moving to 1.7, no packet changes from 1.6.2

1.6.4 -

13w38a/b/c -

13w39a/b - UUIDs added to spawn named entity, game state 'gamemode' byte -> float

13w41a - Large protocol work

Protocol Version

13w41a -

13w39a/b - 80

13w38a/b/c - 79

1.6.4 - 78

1.6.3 - 77

13w37b - 76

13w36a - 75

Packet format

Field Name	Field Type	Notes
Length	VarInt
Type	VarInt
Data

Data Types

VarInt - Protocol Buffer 32-bit Varint

String - UTF-8 String

Handshaking

Serverbound

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Packet ID	Field Name	Field Type	Notes
0x00		VarInt
		String
		VarInt
		VarInt

Play

Clientbound

Keep Alive

Packet ID	Field Name	Field Type	Notes
0x00	Keep Alive ID	Int

Join Game

Packet ID	Field Name	Field Type	Notes
0x01	Entity ID	Int	The player's Entity ID
	Level type	String	level-type in server.properties
	Gamemode	Byte	0: survival, 1: creative, 2: adventure. Bit 3 (0x8) is the hardcore flag
	Dimension	Byte	-1: nether, 0: overworld, 1: end
	Difficulty	Unsigned Byte	0 thru 3 for Peaceful, Easy, Normal, Hard
		Byte
	Max Players	Byte	Used by the client to draw the player list

Chat Message

Packet ID	Field Name	Field Type	Notes
0x02	JSON Data	String	https://gist.github.com/thinkofdeath/e882ce057ed83bac0a1c

Time Update

Packet ID	Field Name	Field Type	Notes
0x03	Age of the world	Long	In ticks; not changed by server commands
	Time of day	Long	The world (or region) time, in ticks. If negative the sun will stop moving at the Math.abs of the time

Entity Equipment

Packet ID	Field Name	Field Type	Notes
0x04	EntityID	Int	Entity's ID
	Slot	Short	Equipment slot: 0=held, 1-4=armor slot (1 - boots, 2 - leggings, 3 - chestplate, 4 - helmet)
	Item	Slot	Item in slot format

Spawn Position

Packet ID	Field Name	Field Type	Notes
0x05	X	Int	Spawn X in block coordinates
	Y	Int	Spawn Y in block coordinates
	Z	Int	in block coordinates

Update Health

Packet ID	Field Name	Field Type	Notes
0x06	Health	Float	0 or less = dead, 20 = full HP
	Food	Short	0 - 20
	Food Saturation	Float	Seems to vary from 0.0 to 5.0 in integer increments

Respawn

Packet ID	Field Name	Field Type	Notes
0x07	Dimension	Int	-1: The Nether, 0: The Overworld, 1: The End
	Difficulty	Byte	0 thru 3 for Peaceful, Easy, Normal, Hard.
	Gamemode	Byte	0: survival, 1: creative, 2: adventure. The hardcore flag is not included
	World Height	Short	Defaults to 256
	Level Type	String

Player

Packet ID	Field Name	Field Type	Notes
0x08	On Ground	True if the client is on the ground, False otherwise

Player Position

Packet ID	Field Name	Field Type	Notes
0x09	X	Double	Absolute position
	Y	Double	Absolute position
	Stance	Double	Used to modify the players bounding box when going up stairs, crouching, etc…
	Z	Double	Absolute position
	On Ground	Bool	True if the client is on the ground, False otherwise

Player Look

Packet ID	Field Name	Field Type	Notes
0x0A	Yaw	Float	Absolute rotation on the X Axis, in degrees
	Pitch	Float	Absolute rotation on the Y Axis, in degrees
	On Ground	Bool	True if the client is on the ground, False otherwise

Player Position And Look

Packet ID	Field Name	Field Type	Notes
0x0B	X	Double	Absolute position
	Y	Double	Absolute position
	Stance	Double	Used to modify the players bounding box when going up stairs, crouching, etc…
	Z	Double	Absolute position
	Yaw	Float	Absolute rotation on the X Axis, in degrees
	Pitch	Float	Absolute rotation on the Y Axis, in degrees
	On Ground	Bool	True if the client is on the ground, False otherwise

Held Item Change

Packet ID	Field Name	Field Type	Notes
0x0C	Slot	Short	The slot which the player has selected (0-8)

Use Bed

Packet ID	Field Name	Field Type	Notes
0x0D	Entity ID	Int	Player ID
		Byte
	X	Int	Bed headboard X as block coordinate
	Y	Unsigned Byte	Bed headboard Y as block coordinate
	Z	Int	Bed headboard Z as block coordinate

Animation

Packet ID	Field Name	Field Type	Notes
0x0E	Entity ID	Int	Player ID
	Animation	Byte	Animation ID

Animation can be one of the following values:

ID	Animation
0	No animation
1	Swing arm
2	Damage animation
3	Leave bed
5	Eat food
6	Critical effect
7	Magic critical effect
102	(unknown)
104	Crouch
105	Uncrouch

Spawn Player

Packet ID	Field Name	Field Type	Notes
0x0F	Entity ID	Int	Player's Entity ID
	Player UUID	String	Player's UUID
	Player Name	String	Player's Name
	X	Int	Player X as a Fixed-Point number
	Y	Int	Player X as a Fixed-Point number
	Z	Int	Player X as a Fixed-Point number
	Yaw	Byte	Player rotation as a packed byte
	Pitch	Byte	Player rotation as a packet byte
	Current Item	Short	The item the player is currently holding. Note that this should be 0 for "no item", unlike -1 used in other packets. A negative value crashes clients.
	Metadata	Metadata	The client will crash if no metadata is sent

Plugin Channels

MC|RPack

Field Name	Field Type	Example	Notes
Resource pack URL	UTF8 string	http://example.com/pack.zip