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 - 0

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 prefixed with a VarInt

Handshaking

Serverbound

Handshake

Packet ID	Field Name	Field Type	Notes
0x00	Protocol Version	VarInt
	Server Address (hostname or IP)	String	localhost
	Server Port	VarInt	25565
	Current state	VarInt	0 for play, 1 for status, 2 for login

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

Collect Item

Packet ID	Field Name	Field Type	Notes
0x10	Collected Entity ID	Int
	Collector Entity ID	Int

Spawn Object

Packet ID	Field Name	Field Type	Notes
0x11	Entity ID	Int	Entity ID of the object
	Type	Byte	The of object (See Objects
	X	Int	X position as a Fixed-Point number
	Y	Int	Y position as a Fixed-Point number
	Z	Int	Z position as a Fixed-Point number
	Pitch	Byte	The pitch in steps of 2p/256
	Yaw	Byte	The yaw in steps of 2p/256
	Data	Object Data

Spawn Mob

Packet ID	Field Name	Field Type	Notes
0x12	Entity ID	Int	Entity's ID
	Type	Unsigned Byte	The type of mob. See Mobs
	X	Int	X position as a Fixed-Point number
	Y	Int	Y position as a Fixed-Point number
	Z	Int	Z position as a Fixed-Point number
	Pitch	Byte	The pitch in steps of 2p/256
	Head Pitch	Byte	The pitch in steps of 2p/256
	Yaw	Byte	The yaw in steps of 2p/256
	Velocity X	Short
	Velocity Y	Short
	Velocity Z	Short
	Metadata	Metadata

Spawn Painting

Packet ID	Field Name	Field Type	Notes
0x13	Entity ID	Int	Entity's ID
	Title	String	Name of the painting. Max length 13
	X	Int	Center X coordinate
	Y	Int	Center Y coordinate
	Z	Int	Center Z coordinate
	Direction	Int	Direction the painting faces (0 -z, 1 -x, 2 +z, 3 +x)

Spawn Experience Orb

Packet ID	Field Name	Field Type	Notes
0x14	Entity ID	Int	Entity's ID
	X	Int	X position as a Fixed-Point number
	Y	Int	Y position as a Fixed-Point number
	Z	Int	Z position as a Fixed-Point number
	Count	Short	The amount of experience this orb will reward once collected

Entity Velocity

Packet ID	Field Name	Field Type	Notes
0x15	Entity ID	Int	Entity's ID
	Velocity X	Short	Velocity on the X axis
	Velocity Y	Short	Velocity on the Y axis
	Velocity Z	Short	Velocity on the Z axis

Destroy Entitie s

Packet ID	Field Name	Field Type	Notes
0x16	Count	Byte	Length of following array
	Entity IDs	Array of Int	The list of entities of destroy

Entity

Packet ID	Field Name	Field Type	Notes
0x17	Entity ID	Int	Entity's ID

Entity Relative Move

Packet ID	Field Name	Field Type	Notes
0x18	Entity ID	Int	Entity's ID
	DX	Byte	Change in X position as a Fixed-Point number
	DY	Byte	Change in Y position as a Fixed-Point number
	DZ	Byte	Change in Z position as a Fixed-Point number

Entity Look

Packet ID	Field Name	Field Type	Notes
0x19	Entity ID	Int	Entity's ID
	Yaw	Byte	The X Axis rotation as a fraction of 360
	Pitch	Byte	The Y Axis rotation as a fraction of 360

Entity Look and Relative Move

Packet ID	Field Name	Field Type	Notes
0x1A	Entity ID	Int	Entity's ID
	DX	Byte	Change in X position as a Fixed-Point number
	DY	Byte	Change in Y position as a Fixed-Point number
	DZ	Byte	Change in Z position as a Fixed-Point number
	Yaw	Byte	The X Axis rotation as a fraction of 360
	Pitch	Byte	The Y Axis rotation as a fraction of 360

Entity Teleport

Packet ID	Field Name	Field Type	Notes
0x1B	Entity ID	Int	Entity's ID
	X	Byte	X position as a Fixed-Point number
	Y	Byte	Y position as a Fixed-Point number
	Z	Byte	Z position as a Fixed-Point number
	Yaw	Byte	The X Axis rotation as a fraction of 360
	Pitch	Byte	The Y Axis rotation as a fraction of 360

Entity Head Look

Packet ID	Field Name	Field Type	Notes
0x1C	Entity ID	Int	Entity's ID
	Head Yaw	Byte	Head yaw in steps of 2p/256

Entity Status

Packet ID	Field Name	Field Type	Notes
0x1D	Entity ID	Int	Entity's ID
	Entity Status	Byte	See below

Entity Status	Meaning
2	Entity hurt
3	Entity dead
6	Wolf taming
7	Wolf tamed
8	Wolf shaking water off itself
9	(of self) Eating accepted by server
10	Sheep eating grass
11	Iron Golem handing over a rose
12	Spawn "heart" particles near a villager
13	Spawn particles indicating that a villager is angry and seeking revenge
14	Spawn happy particles near a villager
15	Spawn a "magic" particle near the Witch
16	Zombie converting into a villager by shaking violently (unused in recent update)
17	A firework exploding

Attach Entity

Packet ID	Field Name	Field Type	Notes
0x1E	Entity ID	Int	Entity's ID
	Vehicle ID	Int	Vechicle's Entity ID
	Leash	Bool	If true leashes the entity to the vehicle

Attach Entity

Packet ID	Field Name	Field Type	Notes
0x1F	Entity ID	Int	Entity's ID
	Metadata	Metadata

Entity Effect

Packet ID	Field Name	Field Type	Notes
0x20	Entity ID	Int	Entity's ID
	Effect ID	Byte	See [[1]]
	Amplifier	Byte
	Duration	Short

Remove Entity Effect

Packet ID	Field Name	Field Type	Notes
0x21	Entity ID	Int	Entity's ID
	Effect ID	Byte

Set Experience

Packet ID	Field Name	Field Type	Notes
0x22	Experience bar	Float	Between 0 and 1
	Level	Short
	Total Experience	Short

Entity Properties

Packet ID	Field Name	Field Type	Notes
0x23	Entity ID	Entity's ID
	Count	Int	Length of following array
	Properties	Array of Property Data

Property Data structure:

Field Name	Field Type	Notes
Key	String
Value	Double
List Length	Short	Number of list elements that follow.
Modifiers	Array of Modifier Data	http://www.minecraftwiki.net/wiki/Attribute#Modifiers

Known key values:

Key	Default	Min	Max	Label
generic.maxHealth	20.0	0.0	Double.MaxValue	Max Health
generic.followRange	32.0	0.0	2048.0	Follow Range
generic.knockbackResistance	0.0	0.0	1.0	Knockback Resistance
generic.movementSpeed	0.699999988079071	0.0	Double.MaxValue	Movement Speed
generic.attackDamage	2.0	0.0	Double.MaxValue
horse.jumpStrength	0.7	0.0	2.0	Jump Strength
zombie.spawnReinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance

Modifier Data structure:

Field Name	Field Type	Notes
UUID	128-bit integer
Amount	Double
Operation	Byte

Chunk Data

Packet ID	Field Name	Field Type	Notes
0x24	Chunk X	Int	Chunk X coordinate
	Chunk Z	Int	Chunk Z coordinate
	Ground-Up continuous	Boolean	This is True if the packet represents all sections in this vertical column, where the primary bit map specifies exactly which sections are included, and which are air
	Primary bit map	Unsigned Short	Bitmask with 1 for every 16x16x16 section which data follows in the compressed data.
	Add bit map	Unsigned Short	Same as above, but this is used exclusively for the 'add' portion of the payload
	Compressed size	Int	Size of compressed chunk data
	Compressed data	Byte array	The chunk data is compressed using Zlib Deflate

Multi Block Change

Packet ID	Field Name	Field Type	Notes
0x25	Chunk X	Int	Chunk X coordinate
	Chunk Z	Int	Chunk Z Coordinate
	Record count	Short	The number of blocks affected
	Data size	Int	The total size of the data, in bytes. Should always be 4*record count
	Records	Array of Records

Record

Bit mask	Width	Meaning
00 00 00 0F	4 bits	Block metadata
00 00 FF F0	12 bits	Block ID
00 FF 00 00	8 bits	Y co-ordinate
0F 00 00 00	4 bits	Z co-ordinate, relative to chunk
F0 00 00 00	4 bits	X co-ordinate, relative to chunk

Block Change

Packet ID	Field Name	Field Type	Notes
0x26	X	Int	Block X Coordinate
	Y	Byte	Block Y Coordinate
	Z	Int	Block Z Coordinate
	Block Type	Short	The new block type for the block
	Block Data	Byte	The new data for the block

Block Action

Packet ID	Field Name	Field Type	Notes
0x27	X	Int	Block X Coordinate
	Y	Byte	Block Y Coordinate
	Z	Int	Block Z Coordinate
	Byte 1	Byte	Varies depending on block - see Block_Actions
	Byte 2	Byte	Varies depending on block - see Block_Actions
	Block Type	Short	The block type for the block

Block Action

Packet ID	Field Name	Field Type	Notes
0x28	Entity ID	Int	Entity's ID
	X	Int	Block Position
	Y	Int
	Z	Int
	Destroy Stage	Byte	0 - 9

Map Chunk Bulk

Packet ID	Field Name	Field Type	Notes
0x29	Chunk column count	Short	The number of chunk in this packet
	Data length	Int	The size of the data field
	Sky light sent	Bool	Whether or not the chunk data contains a light nibble array. This is true in the main world, false in the end + nether
	Data	Byte Array	Compressed chunk data
	Meta information	Meta	See below

Meta

Field Name	Field Type	Notes
Chunk X	Int	The X Coordinate of the chunk
Chunk Z	Int	The Z Coordinate of the chunk
Primary bitmap	Unsigned Short	A bitmap which specifies which sections are not empty in this chunk
Add bitmap	Unsigned Short	A bitmap which specifies which sections need add information because of very high block ids. not yet used

Explosion

Packet ID	Field Name	Field Type	Notes
0x2A	X	Double
	Y	Double
	Z	Double
	Radius	Float	Currently unused in the client
	Record count	Int	This is the count, not the size. The size is 3 times this value.
	Records	(Byte, Byte, Byte) × count	Each record is 3 signed bytes long, each bytes are the XYZ (respectively) offsets of affected blocks.
	Player Motion X	Float	X velocity of the player being pushed by the explosion
	Player Motion Y	Float	Y velocity of the player being pushed by the explosion
	Player Motion Z	Float	Z velocity of the player being pushed by the explosion

Effect

Packet ID	Field Name	Field Type	Notes
0x2B	Effect ID	Int	The ID of the effect, see below.
	X	Int	The X location of the effect multiplied by 8
	Y	Byte	The Y location of the effect multiplied by 8
	Z	Int	The Z location of the effect multiplied by 8
	Data	Int	Extra data for certain effects, see below.
	Disable relative volume	Bool	See above

Sound:

• 1000: random.click
• 1001: random.click
• 1002: random.bow
• 1003: random.door_open or random.door_close (50/50 chance)
• 1004: random.fizz
• 1005: Play a music disc. Data: Record ID
• (1006 not assigned)
• 1007: mob.ghast.charge
• 1008: mob.ghast.fireball
• 1009: mob.ghast.fireball, but with a lower volume.
• 1010: mob.zombie.wood
• 1011: mob.zombie.metal
• 1012: mob.zombie.woodbreak
• 1013: mob.wither.spawn
• 1014: mob.wither.shoot
• 1015: mob.bat.takeoff
• 1016: mob.zombie.infect
• 1017: mob.zombie.unfect
• 1018: mob.enderdragon.end
• 1020: random.anvil_break
• 1021: random.anvil_use
• 1022: random.anvil_land

Particle:

• 2000: Spawns 10 smoke particles, e.g. from a fire. Data: direction, see below
• 2001: Block break. Data: Block ID
• 2002: Splash potion. Particle effect + glass break sound. Data: Potion ID
• 2003: Eye of ender entity break animation - particles and sound
• 2004: Mob spawn particle effect: smoke + flames
• 2005: Spawn "happy villager" effect (hearts).

Smoke directions:

ID	Direction
0	South - East
1	South
2	South - West
3	East
4	(Up or middle ?)
5	West
6	North - East
7	North
8	North - West

Sound Effect

Packet ID	Field Name	Field Type	Notes
0x2C	Sound name	String
	Effect position X	Int	Effect X multiplied by 8
	Effect position Y	Int	Effect Y multiplied by 8
	Effect position Z	Int	Effect Z multiplied by 8
	Volume	Float	1 is 100%, can be more
	Pitch	Byte	63 is 100%, can be more
	Sound Category	Unsigned Byte	Possible values: MASTER: 0 MUSIC: 1 RECORDS: 2 WEATHER: 3 BLOCKS: 4 MOBS: 5 ANIMALS: 6 PLAYERS: 7

Particle

Packet ID	Field Name	Field Type	Notes
0x2D	Particle name	String	The name of the particle to create. A list can be found here
	X	Float	X position of the particle
	Y	Float	Y position of the particle
	Z	Float	Z position of the particle
	Offset X	Float	This is added to the X position after being multiplied by random.nextGaussian()
	Offset Y	Float	This is added to the Y position after being multiplied by random.nextGaussian()
	Offset Z	Float	This is added to the Z position after being multiplied by random.nextGaussian()
	Particle speed	Float	The speed of each particle
	Number of particles	Int	The number of particles to create

Change Game State

Packet ID	Field Name	Field Type	Notes
0x2E	Reason	Byte
	Value	Float	Depends on reason

Reason codes

Code	Effect	Notes
0	Invalid Bed	"tile.bed.notValid"
1	Begin raining
2	End raining
3	Change game mode	"gameMode.changed" 0 - Survival, 1 - Creative, 2 - Adventure
4	Enter credits
5	Demo messages	0 - Show welcome to demo screen, 101 - Tell movement controls, 102 - Tell jump control, 103 - Tell inventory control
Bow hit sound
7	Fade value	The current darkness value. 1 = Dark, 0 = Bright, Setting the value higher causes the game to change color and freeze
8	Fade time	Time in ticks for the sky to fade

Spawn Global Entity

Packet ID	Field Name	Field Type	Notes
0x2F	Entity ID	Int	The entity ID of the thunderbolt
	Type	Byte	The global entity type, currently always 1 for thunderbolt.
	X	Int	Thunderbolt X a fixed-point number
	Y	Int	Thunderbolt Y a fixed-point number
	Z	Int	Thunderbolt Z a fixed-point number

Open Window

Packet ID	Field Name	Field Type	Notes
0x30	Window id	Byte	A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
	Inventory Type	Byte	The window type to use for display. Check below
	Window title	String	The title of the window.
	Number of Slots	Byte	Number of slots in the window (excluding the number of slots in the player inventory).
	Use provided window title	Bool	If false, the client will look up a string like "window.minecart". If true, the client uses what the server provides.
	Entity ID	Int	EntityHorse's entityId. Only sent when window type is equal to 11 (AnimalChest).

See inventory windows for further information.

Close Window

Packet ID	Field Name	Field Type	Notes
0x31	Window id	byte	This is the id of the window that was closed. 0 for inventory.

Set Slot

Packet ID	Field Name	Field Type	Notes
0x32	Window ID	Byte	The window which is being updated. 0 for player inventory. Note that all known window types include the player inventory. This packet will only be sent for the currently opened window while the player is performing actions, even if it affects the player inventory. After the window is closed, a number of these packets are sent to update the player's inventory window (0).
	Slot	Short	The slot that should be updated
	Slot data	Slot

Window Items

Packet ID	Field Name	Field Type	Notes
0x33	Window ID	Byte	The id of window which items are being sent for. 0 for player inventory.
	Count	Short	The number of slots (see below)
	Slot data	Array of Slots

See inventory windows for further information about how slots are indexed.

Window Property

Packet ID	Field Name	Field Type	Notes
0x34	Window ID	Byte	The id of the window.
	Property	Short	Which property should be updated.
	Value	Short	The new value for the property.

Furnace

Properties:

• 0: Progress arrow
• 1: Fire icon (fuel)

Values:

• 0-200 for progress arrow
• 0-200 for fuel indicator

Ranges are presumably in in-game ticks

Enchantment Table

Properties: 0, 1 or 2 depending on the "enchantment slot" being given.

Values: The enchantment's level.

Confirm Transaction

Packet ID	Field Name	Field Type	Notes
0x35	Window ID	Byte	The id of the window that the action occurred in.
	Action number	Short	Every action that is to be accepted has a unique number. This field corresponds to that number.
	Accepted	Bool	Whether the action was accepted.

Update Sign

Packet ID	Field Name	Field Type	Notes
0x36	X	Int	Block X Coordinate
	Y	Short	Block Y Coordinate
	Z	Int	Block Z Coordinate
	Line 1	String	First line of text in the sign
	Line 2	String	Second line of text in the sign
	Line 3	String	Third line of text in the sign
	Line 4	String	Fourth line of text in the sign

Packet ID	Field Name	Field Type	Notes
0x37	Item Type	Short	Type of item being modified
	Item ID	Short	The ID (damage value) of the item being modified
	Text length	Short	Length of following byte array
	Data	Byte Array	Array data

Maps If the first byte of the array is 0, the next two bytes are X start and Y start and the rest of the bytes are the colors in that column.

If the first byte of the array is 1, the rest of the bytes are in groups of three: (data, x, y). The lower half of the data is the type (always 0 under vanilla) and the upper half is the direction.

If the first byte of the array is 2, the second byte is the map scale.

Update Block Entity

Packet ID	Field Name	Field Type	Notes
0x38	X	Int
	Y	Short
	Z	Int
	Action	Byte	The type of update to perform
	Data length	Short	Varies
	NBT Data	Byte Array	Present if data length > 0. Compressed with gzip. Varies

Actions

• 1: Set mob displayed inside a mob spawner. Custom 1 contains the mob type

Tile Editor Open

Packet ID	Field Name	Field Type	Notes
0x39	Tile Entity Id	Byte	Always seems to be 0 (TileEntitySign)
	X	Int	X in block coordinates
	Y	Int	Y in block coordinates
	Z	Int	Z in block coordinates

Statistics

Packet ID	Field Name		Field Type	Notes
0x3A	Count		Int	Number of entrys
	Entry	Statistic's name	String
		Amount	Int	The amount to increase by

Player List Item

Packet ID	Field Name	Field Type	Notes
0x3B	Player name	String	Supports chat colouring, limited to 16 characters.
	Online	Bool	If false, the client will remove the user from the list.
	Ping	Short	Ping, presumably in ms.

Player Abilities

Packet ID	Field Name	Field Type	Notes
0x3C	Flags	Byte
	Flying speed	Float	previous integer value divided by 250
	Walking speed	Float	previous integer value divided by 250

Tab-Complete

Packet ID	Field Name	Field Type	Notes
0x3D	Text	String

Scoreboard Objective

Packet ID	Field Name	Field Type	Notes
0x3E	Objective name	String	An unique name for the objective
	Objective value	String	The text to be displayed for the score.
	Create/Remove	Byte	0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.

Update Score

Packet ID	Field Name	Field Type	Notes
0x3F	Item Name	String	An unique name to be displayed in the list.
	Update/Remove	Byte	0 to create/update an item. 1 to remove an item.
	Score Name	String	The unique name for the scoreboard to be updated. Only sent when Update/Remove does not equal 1.
	Value	Int	The score to be displayed next to the entry. Only sent when Update/Remove does not equal 1.

Display Scoreboard

Packet ID	Field Name	Field Type	Notes
0x40	Position	Byte	The position of the scoreboard. 0 = list, 1 = sidebar, 2 = belowName.
	Score Name	String	The unique name for the scoreboard to be displayed.

Teams

Packet ID	Field Name	Field Type	Notes
0x41	Team Name	String	A unique name for the team. (Shared with scoreboard).
	Mode	Byte	If 0 then the team is created. If 1 then the team is removed. If 2 the team team information is updated. If 3 then new players are added to the team. If 4 then players are removed from the team.
	Team Display Name	String	Only if Mode = 0 or 2.
	Team Prefix	String	Only if Mode = 0 or 2. Displayed before the players' name that are part of this team.
	Team Suffix	String	Only if Mode = 0 or 2. Displayed after the players' name that are part of this team.
	Friendly fire	Byte	Only if Mode = 0 or 2; 0 for off, 1 for on, 3 for seeing friendly invisibles
	Player count	Short	Only if Mode = 0 or 3 or 4. Number of players in the array
	Players	Array of strings	Only if Mode = 0 or 3 or 4. Players to be added/remove from the team.

Plugin Message

Packet ID	Field Name	Field Type	Notes
0x42	Channel	String	Name of the "channel" used to send the data.
	Length	Short	Length of the following byte array
	Data	Byte Array	Any data.

More documentation on this: http://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Disconnect

Packet ID	Field Name	Field Type	Notes
0x43	Reason	String	Displayed to the client when the connection terminates

Serverbound

Keep Alive

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

Chat Message

Packet ID	Field Name	Field Type	Notes
0x01	JSON Data	String	https://gist.github.com/thinkofdeath/e882ce057ed83bac0a1c

?

Packet ID	Field Name	Field Type	Notes
0x02		Int
		Byte

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

Player

Packet ID	Field Name	Field Type	Notes
0x03	On Ground	True if the client is on the ground, False otherwise

Player Position

Packet ID	Field Name	Field Type	Notes
0x04	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
0x05	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
0x06	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

Use Bed

Packet ID	Field Name	Field Type	Notes
0x07	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

Player Block Placement

Packet ID	Field Name	Field Type	Notes
0x08	X	Int	Block position
	Y	Unsigned Byte	Block position
	Z	Int	Block position
	Direction	Byte	The offset to use for block/item placement (see below)
	Held item	Slot
	Cursor position X	Byte	The position of the crosshair on the block
	Cursor position Y	Byte
	Cursor position Z	Byte

In normal operation (ie placing a block), this packet is sent once, with the values set normally.

This packet has a special case where X, Y, Z, and Direction are all -1. (Note that Y is unsigned so set to 255.) This special packet indicates that the currently held item for the player should have its state updated such as eating food, shooting bows, using buckets, etc.

In a Notchian Beta client, the block or item ID corresponds to whatever the client is currently holding, and the client sends one of these packets any time a right-click is issued on a surface, so no assumptions can be made about the safety of the ID. However, with the implementation of server-side inventory, a Notchian server seems to ignore the item ID, instead operating on server-side inventory information and holding selection. The client has been observed (1.2.5 and 1.3.2) to send both real item IDs and -1 in a single session.

Special note on using buckets: When using buckets, the Notchian client might send two packets: first a normal and then a special case. The first normal packet is sent when you're looking at a block (e.g. the water you want to scoop up). This normal packet does not appear to do anything with a Notchian server. The second, special case packet appears to perform the action - based on current position/orientation and with a distance check - it appears that buckets can only be used within a radius of 6 units.

Held Item Change

Packet ID	Field Name	Field Type	Notes
0x09	Slot	Short	The slot which the player has selected (0-8)

Animation

Packet ID	Field Name	Field Type	Notes
0x0A	Entity ID	Int	Player ID
	Animation	Byte	Animation ID

Entity Action

Packet ID	Field Name	Field Type	Notes
0x0B	Entity ID	Int	Player ID
	Action ID	Byte	The ID of the action, see below.
	Jump Boost	Int	Horse jump boost. Ranged from 0 -> 100.

Action ID can be one of the following values:

ID	Action
1	Crouch
2	Uncrouch
3	Leave bed
4	Start sprinting
5	Stop sprinting

Steer Vehicle

Packet ID	Field Name	Field Type	Notes
0x0C	Sideways	Float	Positive to the left of the player
	Forward	Float	Positive forward
	Jump	Bool
	Unmount	Bool	True when leaving the vehicle

Close Window

Packet ID	Field Name	Field Type	Notes
0x0D	Window id	byte	This is the id of the window that was closed. 0 for inventory.

Click Window

Packet ID	Field Name	Field Type	Notes
0x0E	Window ID	Byte	The id of the window which was clicked. 0 for player inventory.
	Slot	Short	The clicked slot. See below.
	Button	Byte	The button used in the click. See below.
	Action number	Short	A unique number for the action, used for transaction handling (See the Transaction packet).
	Mode	Byte	Inventory operation mode. See below.
	Clicked item	Slot

See inventory windows for further information about how slots are indexed.

When right-clicking on a stack of items, half the stack will be picked up and half left in the slot. If the stack is an odd number, the half left in the slot will be smaller of the amounts.

The Action number is actually a counter, starting at 1. This number is used by the server as a transaction ID to send back a Transaction packet.

The distinct type of click performed by the client is determined by the combination of the "Mode" and "Button" fields.

Mode	Button	Slot	Trigger
0	0	Normal	Left mouse click
	1	Normal	Right mouse click
1	0	Normal	Shift + left mouse click
	1	Normal	Shift + right mouse click (Identical behavior)
2	0	Normal	Number key 1
	1	Normal	Number key 2
	2	Normal	Number key 3
	...	...	...
	8	Normal	Number key 9
3	2	Normal	Middle click
4	0	Normal	Drop key (Q)
	1	Normal	Ctrl + Drop key (Ctrl-Q)
	0	-999	Left click outside inventory holding nothing (No-op)
	1	-999	Right click outside inventory holding nothing (No-op)
5	0	-999	Starting left mouse drag (Or middle mouse)
	4	-999	Starting right mouse drag
	1	Normal	Add slot for left-mouse drag
	5	Normal	Add slot for right-mouse drag
	2	-999	Ending left mouse drag
	6	-999	Ending right mouse drag
6	0	Normal	Double click

Starting from version 1.5, "painting mode" is available for use in inventory windows. It is done by picking up stack of something (more than 1 items), then holding mouse button (left, right or middle) and dragging holded stack over empty (or same type in case of right button ) slots. In that case client sends the following to server after mouse button release (omitting first pickup packet which is sent as usual):

1. packet with mode 5, slot -999 , button (0 for left | 4 for right);
2. packet for every slot painted on, mode is still 5, button (1 | 5);
3. packet with mode 5, slot -999, button (2 | 6);

If any of the painting packets other than the "progress" ones are sent out of order (for example, a start, some slots, then another start; or a left-click in the middle) the painting status will be reset.

Confirm Transaction

Packet ID	Field Name	Field Type	Notes
0x0F	Window ID	Byte	The id of the window that the action occurred in.
	Action number	Short	Every action that is to be accepted has a unique number. This field corresponds to that number.
	Accepted	Bool	Whether the action was accepted.

Creative Inventory Action

Packet ID	Field Name	Field Type	Notes
0x10	Slot	Short	Inventory slot
	Clicked item	Slot

Enchant Item

Packet ID	Field Name	Field Type	Notes
0x11	Window ID	Byte	The ID sent by Open Window
	Enchantment	Byte	The position of the enchantment on the enchantment table window, starting with 0 as the topmost one.

Update Sign

Packet ID	Field Name	Field Type	Notes
0x12	X	Int	Block X Coordinate
	Y	Short	Block Y Coordinate
	Z	Int	Block Z Coordinate
	Line 1	String	First line of text in the sign
	Line 2	String	Second line of text in the sign
	Line 3	String	Third line of text in the sign
	Line 4	String	Fourth line of text in the sign

Player Abilities

Packet ID	Field Name	Field Type	Notes
0x13	Flags	Byte
	Flying speed	Float	previous integer value divided by 250
	Walking speed	Float	previous integer value divided by 250

Tab-Complete

Packet ID	Field Name	Field Type	Notes
0x14	Text	String

Client Settings

Packet ID	Field Name	Field Type	Notes
0x15	Locale	String	en_GB
	View distance	Byte	0-3 for 'far', 'normal', 'short', 'tiny'.
	Chat flags	Byte	Chat settings. See notes below.
	???	Bool	???
	Difficulty	Byte	Client-side difficulty from options.txt
	Show Cape	Bool	Client-side "show cape" option

Chat flags has several values packed into one byte.

Chat Enabled: Bits 0-1. 00: Enabled. 01: Commands only. 10: Hidden.

Colors Enabled: Bit 3. 0: Disabled. 1: Enabled.

?

Packet ID	Field Name	Field Type	Notes
0x16		Byte

?

Packet ID	Field Name	Field Type	Notes
0x17		String
	Length	Short
		Array of Bytes

Status

Clientbound

?

Packet ID	Field Name	Field Type	Notes
0x00		String

?

Packet ID	Field Name	Field Type	Notes
0x01		Long

Serverbound

?

Packet ID	Field Name	Field Type	Notes
0x00

?

Packet ID	Field Name	Field Type	Notes
0x01		Long

Login

Clientbound

?

Packet ID	Field Name	Field Type	Notes
0x00		String

?

Packet ID	Field Name	Field Type	Notes
0x01		String
	Length	Short
		Byte array
	Length	Short
		Byte array

?

Packet ID	Field Name	Field Type	Notes
0x02	UUID	String
	Name	String

Serverbound

?

Packet ID	Field Name	Field Type	Notes
0x00	Name	String

?

Packet ID	Field Name	Field Type	Notes
0x01	Length	Short
		Byte array
	Length	Short
		Byte array

Plugin Channels

MC|RPack

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