Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.8.8, protocol 47) to the current pre-release (currently 15w36d, protocol 70). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One 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 occurred to the respective packets there.

Contents

Data types

• Chunk Section
• Entity Metadata

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x0E 0x00	Spawn Object	Current	Pre
0x11 0x01	Spawn Experience Orb	Current	(unchanged)
0x2C 0x02	Spawn Global Entity	Current	(unchanged)
0x0F 0x03	Spawn Mob	Current	Pre
0x10 0x04	Spawn Painting	Current	(unchanged)
0x0C 0x05	Spawn Player	Current	Pre
0x0B 0x06	Animation	Current	(unchanged)
0x37 0x07	Statistics	Current	(unchanged)
0x25 0x08	Block Break Animation	Current	(unchanged)
0x35 0x09	Update Block Entity	Current	(unchanged)
0x24 0x0A	Block Action	Current	(unchanged)
0x23 0x0B	Block Change	Current	(unchanged)
0x0C	Boss Bar		Pre
0x41 0x0D	Server Difficulty	Current	(unchanged)
0x3A 0x0E	Tab-Complete	Current	(unchanged)
0x02 0x0F	Chat Message	Current	(unchanged)
0x22 0x10	Multi Block Change	Current	(unchanged)
0x32 0x11	Confirm Transaction	Current	(unchanged)
0x2E 0x12	Close Window	Current	(unchanged)
0x2D 0x13	Open Window	Current	(unchanged)
0x30 0x14	Window Items	Current	(unchanged)
0x31 0x15	Window Property	Current	(unchanged)
0x2F 0x16	Set Slot	Current	(unchanged)
0x17	Set Cooldown		Pre
0x3F 0x18	Plugin Message	Current	(unchanged)
0x40 0x19	Disconnect	Current	(unchanged)
0x1A	Entity Status	Current	Pre
0x27 0x1B	Explosion	Current	(unchanged)
0x1C	Unload Chunk		Pre
0x46 0x1D	Set Compression	Current	(unchanged)
0x2B 0x1E	Change Game State	Current	(unchanged)
0x00 0x1F	Keep Alive	Current	(unchanged)
0x21 0x20	Chunk Data	Current	Pre
0x28 0x21	Effect	Current	(unchanged)
0x2A 0x22	Particle	Current	(unchanged)
0x29 0x23	Sound Effect	Current	(unchanged)
0x01 0x24	Join Game	Current	(unchanged)
0x34 0x25	Map	Current	Pre
0x15 0x26	Entity Relative Move	Current	(unchanged)
0x17 0x27	Entity Look And Relative Move	Current	(unchanged)
0x16 0x28	Entity Look	Current	(unchanged)
0x14 0x29	Entity	Current	(unchanged)
0x36 0x2A	Open Sign Editor	Current	(unchanged)
0x39 0x2B	Player Abilities	Current	(unchanged)
0x42 0x2C	Combat Event	Current	Pre
0x38 0x2D	Player List Item	Current	(unchanged)
0x08 0x2E	Player Position And Look	Current	(unchanged)
0x0A 0x2F	Use Bed	Current	(unchanged)
0x13 0x30	Destroy Entities	Current	(unchanged)
0x1E 0x31	Remove Entity Effect	Current	(unchanged)
0x48 0x32	Resource Pack Send	Current	(unchanged)
0x07 0x33	Respawn	Current	(unchanged)
0x19 0x34	Entity Head Look	Current	(unchanged)
0x44 0x35	World Border	Current	(unchanged)
0x43 0x36	Camera	Current	(unchanged)
0x09 0x37	Held Item Change	Current	(unchanged)
0x3D 0x38	Display Scoreboard	Current	(unchanged)
0x1C 0x39	Entity Metadata	Current	(unchanged)
0x1B 0x3A	Attach Entity	Current	(unchanged)
0x12 0x3B	Entity Velocity	Current	(unchanged)
0x04 0x3C	Entity Equipment	Current	Pre
0x1F 0x3D	Set Experience	Current	(unchanged)
0x06 0x3E	Update Health	Current	(unchanged)
0x3B 0x3F	Scoreboard Objective	Current	(unchanged)
0x3E 0x40	Teams	Current	Pre
0x3C 0x41	Update Score	Current	(unchanged)
0x05 0x42	Spawn Position	Current	(unchanged)
0x03 0x43	Time Update	Current	(unchanged)
0x45 0x44	Title	Current	(unchanged)
0x33 0x45	Update Sign	Current	(unchanged)
0x47 0x46	Player List Header And Footer	Current	(unchanged)
0x0D 0x47	Collect Item	Current	(unchanged)
0x18 0x48	Entity Teleport	Current	(unchanged)
0x20 0x49	Entity Properties	Current	Pre
0x1D 0x4A	Entity Effect	Current	(unchanged)
0x26	Map Chunk Bulk	Current
0x49	Update Entity NBT	Current
Play serverbound
0x14 0x00	Tab-Complete	Current	(unchanged)
0x01	Chat Message	Current	(unchanged)
0x16 0x02	Client Status	Current	Pre
0x15 0x03	Client Settings	Current	Pre
0x0F 0x04	Confirm Transaction	Current	(unchanged)
0x11 0x05	Enchant Item	Current	(unchanged)
0x0E 0x06	Click Window	Current	(unchanged)
0x0D 0x07	Close Window	Current	(unchanged)
0x17 0x08	Plugin Message	Current	(unchanged)
0x02 0x09	Use Entity	Current	Pre
0x00 0x0A	Keep Alive	Current	(unchanged)
0x04 0x0B	Player Position	Current	(unchanged)
0x06 0x0C	Player Position And Look	Current	(unchanged)
0x05 0x0D	Player Look	Current	(unchanged)
0x03 0x0E	Player	Current	(unchanged)
0x13 0x0F	Player Abilities	Current	(unchanged)
0x07 0x10	Player Digging	Current	Pre
0x0B 0x11	Entity Action	Current	Pre
0x0C 0x12	Steer Vehicle	Current	(unchanged)
0x19 0x13	Resource Pack Status	Current	(unchanged)
0x09 0x14	Held Item Change	Current	(unchanged)
0x10 0x15	Creative Inventory Action	Current	(unchanged)
0x12 0x16	Update Sign	Current	Pre
0x0A 0x17	Animation	Current	Pre
0x08 0x19	Player Block Placement	Current	Pre
0x1A	Use Item		Pre
Status clientbound
0x00	Response	Current	(unchanged)
0x01	Pong	Current	(unchanged)
Status serverbound
0x00	Request	Current	(unchanged)
0x01	Ping	Current	(unchanged)
Login clientbound
0x00	Disconnect	Current	(unchanged)
0x01	Encryption Request	Current	(unchanged)
0x02	Login Success	Current	(unchanged)
0x03	Set Compression	Current	(unchanged)
Login serverbound
0x00	Login Start	Current	(unchanged)
0x01	Encryption Response	Current	(unchanged)

New/modified data types

Chunk Section

Format is now:

Field Name	Field Type	Notes
Bits Per Block	Unsigned Byte	How many bits per block in Data Array. If 0, the Palette Length and Palette fields are omitted and the global palette (with 13 bits per block) is used.
Palette Length	Optional VarInt	Length of the following array
Palette	Optional Array of VarInt	Mapping of block state IDs in the global palette (type = x >> 4, meta = x & 15) to indices of this array
Data Array Length	VarInt	Number of bytes in the following array, divided by 8 (given as such because Notchian implements Data Array as an Array of Long)
Data Array	Byte Array	List of 4096 indices pointing to state IDs in the Palette, followed by padding to round the length up to the next multiple of 8 bytes
Block Light	Byte Array	Half byte per block
Sky Light	Optional Byte Array	Only if in the Overworld; half byte per block

Data Array, Block Light, and Sky Light are given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates.

Entity Metadata

Format is now an array of entries, each of which looks like the following:

Name	Type	Meaning
Index	Unsigned Byte	Unique index key determining the meaning of the following value, see the table below. If this is 0xff then the it is the end of the Entity Metadata array and no more is read.
Type	Optional Byte Enum	Only if Index is not 0xff; the type of the index, see the table below
Value	Optional value of Type	Only if Index is not 0xff: the value of the metadata field

Value of Type field	Type of Value field	Notes
0	Byte
1	VarInt
2	Float
3	String
4	Chat
5	Slot
6	Boolean
7	Vector3F (Array of Float)	3 elements
8	Position
9	OptPosition (Boolean + Optional Position)	Position is present if the Boolean is set to true
10	Direction (VarInt)	???
11	OptUUID (Boolean + Optional UUID)	UUID is present if the Boolean is set to true
12	BlockID	id << 4 | data

Entity class	Index	Type	Meaning
Entity	0	Byte	Unknown
	1	VarInt	Unknown
	2	String	Unknown
	3	Boolean	Unknown
	4	Boolean	Unknown
AreaEffectCloud extends Entity	5	Float	Unknown
	6	VarInt	Unknown
	7	Boolean	Unknown
	8	VarInt	Unknown
Arrow extends Entity	5	Byte	Unknown
TippedArrow extends Arrow	6	VarInt	Unknown
Boat extends Entity	5	VarInt	Unknown
	6	VarInt	Unknown
	7	Float	Unknown
EnderCrystal extends Entity	5	OptPosition	Unknown
Fireball extends Entity	no additional metadata
WitherSkull extends Fireball	5	Boolean	Unknown
Fireworks extends Entity	5	Slot	Unknown
Hanging extends Entity	no additional metadata
ItemFrame extends Hanging	5	Slot	Unknown
	6	VarInt	Unknown
Item extends Entity	5	Slot	Unknown
Living extends Entity	5	Byte	Unknown
	6	Float	Unknown
	7	VarInt	Unknown
	8	Boolean	Unknown
	9	VarInt	Unknown
ArmorStand extends Living	10	Byte	Unknown
	11	Vector3F	Unknown
	12	Vector3F	Unknown
	13	Vector3F	Unknown
	14	Vector3F	Unknown
	15	Vector3F	Unknown
	16	Vector3F	Unknown
Insentient extends Living	10	Byte	Unknown
Ambient extends Insentient	no additional metadata
Bat extends Ambient	11	Byte	Unknown
Creature extends Insentient	no additional metadata
Ageable extends Creature	11	Boolean	Unknown
Animal extends Ageable	no additional metadata
Horse extends Animal	12	Byte	Unknown
	13	VarInt	Unknown
	14	VarInt	Unknown
	15	OptUUID	Unknown
	16	VarInt	Unknown
Pig extends Animal	12	Boolean	Unknown
Rabbit extends Animal	12	VarInt	Unknown
Sheep extends Animal	12	Byte	Unknown
TameableAnimal extends Animal	12	Byte	Unknown
	13	OptUUID	Unknown
Ocelot extends TameableAnimal	14	VarInt	Unknown
Wolf extends TameableAnimal	14	Float	Unknown
	15	Boolean	Unknown
	16	VarInt	Unknown
Villager extends Ageable	12	VarInt	Unknown
Golem extends Creature	no additional metadata
IronGolem extends Golem	11	Byte	Unknown
Shulker extends Golem	11	Direction	Unknown
	12	OptPosition	Unknown
	13	Byte	Unknown
Monster extends Creature	no additional metadata
Blaze extends Monster	11	Byte	Unknown
Creeper extends Monster	11	VarInt	Unknown
	12	Boolean	Unknown
	13	Boolean	Unknown
Guardian extends Monster	11	Byte	Unknown
	12	VarInt	Unknown
Skeleton extends Monster	11	VarInt	Unknown
	12	Boolean	Unknown
Spider extends Monster	11	Byte	Unknown
Witch extends Monster	11	Boolean	Unknown
Wither extends Monster	11	VarInt	Unknown
	12	VarInt	Unknown
	13	VarInt	Unknown
	14	VarInt	Unknown
Zombie extends Monster	11	Boolean	Unknown
	12	Boolean	Unknown
	13	Boolean	Unknown
Enderman extends Monster	11	Block ID	Unknown
	12	Boolean	Unknown
EnderDragon extends Insentient	11	VarInt	Unknown
Flying extends Insentient	no additional metadata
Ghast extends Flying	11	Boolean	Unknown
Slime extends Insentient	11	VarInt	Unknown
Minecart extends Entity	5	VarInt	Unknown
	6	VarInt	Unknown
	7	Float	Unknown
	8	VarInt	Unknown
	9	VarInt	Unknown
	10	Boolean	Unknown
MinecartCommandBlock extends Minecart	11	String	Unknown
	12	Chat	Unknown
MinecartFurnace extends Minecart	11	Boolean	Unknown
TNTPrimed extends Entity	5	VarInt	Unknown

Entity classes also recursively use fields from classes they extend.

Handshaking

Clientbound

No changes so far.

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Handshaking	Server	Protocol Version	VarInt	See protocol version numbers (currently 47 70)
			Server Address	String	hostname or IP, e.g. localhost or 127.0.0.1
			Server Port	Unsigned Short	default is 25565
			Next State	VarInt Enum	1 for status, 2 for login

Play

Clientbound

Entity Equipment

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x04	Play	Client	Entity ID	VarInt	Entity's EID
			Slot	Short VarInt Enum	Equipment slot. 0: main hand, 1: off hand, 1–4 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
			Item	Slot

Spawn Player

This packet is sent by the server when a player comes into visible range, not when a player joins.

This packet must be sent after the Player List Item (Play, 0x38, clientbound) packet that adds the player data for the client to use when spawning a player. If the Player List Item for the player spawned by this packet is not present when this packet arrives, Notchian clients will not spawn the player entity. The Player List Item packet includes skin/cape data.

Servers can, however, safely spawn player entities for players not in visible range. The client appears to handle it correctly.

When in online-mode the UUIDs must be valid and have valid skin blobs, in offline-mode UUID v3 is used.

For NPCs UUID v2 should be used. Note:

<+Grum> i will never confirm this as a feature you know that :)

In an example UUID, xxxxxxxx-xxxx-Yxxx-xxxx-xxxxxxxxxxxx, the UUID version is specified by Y. So, for UUID v3, Y will always be 3, and for UUID v2, Y will always be 2.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0C	Play	Client	Entity ID	VarInt	Player's EID
			Player UUID	UUID
			X	Int	Player X as a Fixed-Point number
			Y	Int	Player Y as a Fixed-Point number
			Z	Int	Player Z as a Fixed-Point number
			Yaw	Angle
			Pitch	Angle
			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.
			Metadata	Entity Metadata

Spawn Object

Sent by the server when an object/vehicle is created.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0E	Play	Client	Entity ID	VarInt	EID of the object
			Object UUID	UUID
			Type	Byte	The type of object (See Entities#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	Angle
			Yaw	Angle
			Data	Object Data
			Info	Int	Depends on Type; see Object Data#Meaning of int field
			Velocity X	Short
			Velocity Y	Short
			Velocity Z	Short

Spawn Mob

Sent by the server when a mob entity is spawned.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F	Play	Client	Entity ID	VarInt
			Entity UUID	UUID
			Type	Unsigned Byte	The type of mob. See Entities#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
			Yaw	Angle
			Pitch	Angle
			Head Pitch	Angle
			Velocity X	Short	Same units as Entity Velocity
			Velocity Y	Short	Same units as Entity Velocity
			Velocity Z	Short	Same units as Entity Velocity
			Metadata	Entity Metadata

Entity Status

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1A	Play	Client	Entity ID	Int
			Entity Status	Byte Enum	See below

Entity Status	Meaning
1	Sent when resetting a mob spawn minecart's timer — appears to be unused by the client
2	Living Entity hurt
3	Living Entity dead
4	Iron Golem throwing up arms
6	Wolf/Ocelot/Horse taming — Spawn “heart” particles
7	Wolf/Ocelot/Horse tamed — Spawn “smoke” particles
8	Wolf shaking water — Trigger the shaking animation
9	(of self) Eating accepted by server
10	Sheep eating grass
10	Play TNT ignite sound
11	Iron Golem handing over a rose
12	Villager mating — Spawn “heart” particles
13	Spawn particles indicating that a villager is angry and seeking revenge
14	Spawn happy particles near a villager
15	Witch animation — Spawn “magic” particles
16	Play zombie converting into a villager sound
17	Firework exploding
18	Animal in love (ready to mate) — Spawn “heart” particles
19	Reset squid rotation
20	Spawn explosion particle — works for some living entities
21	Play guardian sound — works for every entity
22	Enables reduced debug for players
23	Disables reduced debug for players
24–28	Sets op permission level 0–4 for players

Entity Properties

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x20	Play	Client	Entity ID		VarInt
			Number Of Properties		Int		Number of elements in the following array
			Property	Key	Array	String	See below
				Value		Double	See below
				Number Of Modifiers		VarInt	Number of elements in the following array
				Modifiers		Array of Modifier Data	Modifier Data defined below

Known Key values (see also Attribute#Modifiers):

Key	Default	Min	Max	Label
generic.maxHealth	20.0	0.0	Double.MaxValue 1024.0	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 1024.0	Movement Speed
generic.attackDamage	2.0	0.0	Double.MaxValue 2048.0	Attack Damage
generic.attackSpeed	4.0	0.0	1024.0	Attack Speed
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	UUID
Amount	Double
Operation	Byte

Chunk Data

Chunk pillars are not unloaded by the client automatically. To unload chunk pillars, send this packet with Ground-Up Continuous=true and no 16^3 chunks (eg. Primary Bit Mask=0) send an Unload Chunk packet with the chunk's X and Z coordinates. The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimenison the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x21	Play	Client	Chunk X	Int	Chunk X coordinate
			Chunk Z	Int	Chunk Z coordinate
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	Unsigned Short VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data follows in the compressed data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.

Unload Chunk

Tells the client to unload a chunk.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Chunk X	Int	Chunk X coordinate
			Chunk Z	Int	Chunk Z coordinate

Multi Block Change

Fired whenever 2 or more blocks are changed within the render distance.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x22 0x23	Play	Client	Chunk X		Int		Chunk X coordinate
			Chunk Z		Int		Chunk Z coordinate
			Record Count		VarInt		Number of elements in the following array, i.e. the number of blocks affected
			Record	Horizontal Position	Array	Unsigned Byte	The 4 most significant bits (0xF0) encode the X coordinate, relative to the chunk. The 4 least significant bits (0x0F) encode the Z coordinate, relative to the chunk.
				Y Coordinate		Unsigned Byte
				Block ID		VarInt	The new block state ID for the block as given in the global palette (type = x >> 4, meta = x & 15)

Block Change

Fired whenever a block is changed within the render distance.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x23 0x24	Play	Client	Location	Position	Block Coordinates
			Block ID	VarInt	The new block state ID for the block as given in the global palette (type = x >> 4, meta = x & 15)

Block Action

This packet is used for a number of things:

• Chests opening and closing
• Pistons pushing and pulling
• Note blocks playing
• Updating beacons

See also: Block Actions

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x24 0x25	Play	Client	Location	Position	Block coordinates
			Byte 1	Unsigned Byte	Varies depending on block — see Block Actions
			Byte 2	Unsigned Byte	Varies depending on block — see Block Actions
			Block Type	VarInt

Block Break Animation

0–9 are the displayable destroy stages and each other number means that there is no animation on this coordinate.

You can also set an animation to air! The animation will still be visible.

If you need to display several break animations at the same time you have to give each of them a unique Entity ID.

Also if you set the coordinates to a special block like water etc. it won't show the actual break animation but some other interesting effects. For example, water will lose its transparency.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x25 0x26	Play	Client	Entity ID	VarInt	EID for the animation
			Location	Position	Block Position
			Destroy Stage	Byte	0–9 to set it, any other value to remove it

Map Chunk Bulk

Replaced by multiple Chunk Data packets.

Map

Updates a rectangular area on a map item.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x34	Play	Client	Item Damage		VarInt		The damage value (map ID) of the map being modified
			Scale		Byte		From 0 for a fully zoomed-in map (1 block per pixel) to 4 for a fully zoomed-out map (16 blocks per pixel)
			Tracking Position		Boolean		Specifies whether the icons are shown
			Icon Count		VarInt		Number of elements in the following array
			Icon	Direction And Type	Array	Byte	0xF0 = Direction, 0x0F = Type
				X		Byte
				Z		Byte
			Columns		Byte		Number of columns updated
			Rows		Optional Byte		Only if Columns is more than 0; number of rows updated
			X		Optional Byte		Only if Columns is more than 0; x offset of the westernmost column
			Z		Optional Byte		Only if Columns is more than 0; z offset of the northernmost row
			Length		Optional VarInt		Only if Columns is more than 0; length of the following array
			Data		Optional Array of Byte Enum		Only if Columns is more than 0; see Map item format

Teams

Creates and updates teams.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x3E	Play	Client	Team Name	String	A unique name for the team. (Shared with scoreboard).
			Mode	Byte Enum	0: create team, 1: remove team, 2: update team info; 3: add players to team; 4: remove players from team
			Team Display Name	Optional String	Only if Mode is 0 or 2.
			Team Prefix	Optional String	Only if Mode is 0 or 2. Displayed before the players' name that are part of this team.
			Team Suffix	Optional String	Only if Mode is 0 or 2. Displayed after the players' name that are part of this team.
			Friendly Fire	Optional Byte	Only if Mode is 0 or 2. 0 for off, 1 for on, 3 for seeing friendly invisibles.
			Name Tag Visibility	Optional String	Only if Mode is 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
			Collision Rule	Optional String	Only if Mode is 0 or 2. always, hideForOtherTeams (sic), hideForOwnTeam (sic), never
			Color	Optional Byte	Only if Mode is 0 or 2. Same as Chat colors.
			Player Count	Optional VarInt	Only if Mode is 0 or 3 or 4. Number of players in the array.
			Players	Optional Array of String	Only if Mode is 0 or 3 or 4. Players to be added/remove from the team. Max 40 characters so may be uuid's later.

Combat Event

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x42	Play	Client	Event		VarInt Enum	Determines the layout of the remaining packet
			Event	Field Name
			0: enter combat	no fields	no fields
			1: end combat	Duration	VarInt
				Entity ID	Int
			2: entity dead	Player ID	VarInt
				Entity ID	Int
				Message	String Chat

Update Entity NBT

Was only used to update boss bars, replaced by Boss Bar accordingly.

Boss Bar

This packet replaces Update Entity NBT packet which has been removed.

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x49	Play	Client	UUID		UUID	Unique ID for this bar
			Action		VarInt Enum	Determines the layout of the remaining packet
			Action	Field Name
			0: add	Title	Chat
				Health	Float	From 0 to 1. Values greater than 1 do not crash the client, and start rendering part of a second health bar at around 1.5.
				Color	VarInt	Color ID (see below)
				Dividers	VarInt	Number of dividers rendered in the bar
				Flags	Unsigned Byte	Bit mask: 0x1 should darken sky, 0x2: is dragon bar
			1: remove	no fields	no fields	Removes this boss bar
			2: update health	Health	Float	as above
			3: update title	Title	Chat
			4: update style	Color	VarInt Enum	Color ID (see below)
				Dividers	VarInt	as above
			5: update flags	Flags	Unsigned Byte	as above

ID	Color
0	Pink(ish)
1	Cyan
2	Red
3	Lime
4	Yellow
5	Purple
6	White

Set Cooldown

Applies a cooldown period to an item type.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x4A	Play	Client	Item ID	VarInt	ID of the item to apply a cooldown to.
			Cooldown Ticks	VarInt	Number of ticks to apply a cooldown for.

Serverbound

Use Entity

This packet is sent from the client to the server when the client attacks or right-clicks another entity (a player, minecart, etc).

A Notchian server only accepts this packet if the entity being attacked/used is visible without obstruction and within a 4-unit radius of the player's position.

Note that middle-click in creative mode is interpreted by the client and sent as a Creative Inventory Action packet instead.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Server	Target	VarInt
			Type	VarInt Enum	0: interact, 1: attack, 2: interact at
			Target X	Optional Float	Only if Type is interact at
			Target Y	Optional Float	Only if Type is interact at
			Target Z	Optional Float	Only if Type is interact at
			Hand	Optional VarInt Enum	Only if Type is interact or interact at; 0: main hand, 1: off hand

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius of the player's position.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x07	Play	Server	Status	Byte Enum	The action the player is taking against the block (see below)
			Location	Position	Block position
			Face	Byte Enum	The face being hit (see below)

Status can be one of seven values:

Value	Meaning	Notes
0	Started digging
1	Cancelled digging	Sent when the player lets go of the Mine Block key (default: left click)
2	Finished digging	Sent when the client thinks it is finished
3	Drop item stack	Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: depends on OS). Location is always set to 0/0/0, Face is always set to -Y.
4	Drop item	Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y.
5	Shoot arrow / finish eating	Location is always set to 0/0/0, Face is always set to Special.
6	Swap item in hand	Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y.

The Face field can be one of the following values, representing the face being hit (or the Special value used for “shoot arrow / finish eating”):

Value	Offset	Face
0	-Y	Bottom
1	+Y	Top
2	-Z	North
3	+Z	South
4	-X	West
5	+X	East
255	—	Special

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08	Play	Server	Hand	VarInt Enum	Hand used for the animation

Player Block Placement

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08 0x09	Play	Server	Location	Position	Block position
			Face	Byte VarInt Enum	The face on which the block is placed (as documented at Player Digging)
			Held Item	Slot
			Hand	VarInt Enum	The hand from which the block is placed; 0: main hand, 1: off hand
			Cursor Position X	Byte	The position of the crosshair on the block
			Cursor Position Y	Byte
			Cursor Position Z	Byte

In normal operation (i.e. 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, pulling back bows, using buckets, etc.

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

Sent when the player changes the slot selection.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x09 0x0A	Play	Server	Slot	Short	The slot which the player has selected (0–8)

Animation

Sent when the player's arm swings.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0A 0x0B	Play	Server	Hand	VarInt Enum	Hand used for the animation

Entity Action

Sent at least when crouching, leaving a bed, or sprinting. To send action animation to client use 0x28. The client will send this with Action ID = 3 when “Leave Bed” is clicked.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0B 0x0C	Play	Server	Entity ID	VarInt	Player ID
			Action ID	VarInt Enum	The ID of the action, see below
			Jump Boost	VarInt	Horse jump boost. Ranged from 0 to 100.

Action ID can be one of the following values:

ID	Action
0	Crouch
1	Uncrouch
2	Leave bed
3	Start sprinting
4	Stop sprinting
5	Jump with horse
6	Open inventory

“Open inventory” is now sent via the Client Status packet.

Steer Vehicle

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0C 0x0D	Play	Server	Sideways	Float	Positive to the left of the player
			Forward	Float	Positive forward
			Flags	Unsigned Byte	Bit mask. 0x1: jump, 0x2: unmount

Close Window

This packet is sent by the client when closing a window.

Notchian clients send a Close Window packet with Window ID 0 to close their inventory even though there is never an Open Window packet for the inventory.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0D 0x0E	Play	Server	Window ID	Unsigned Byte	This is the ID of the window that was closed. 0 for player inventory.

Click Window

This packet is sent by the player when it clicks on a slot in a window.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0E 0x0F	Play	Server	Window ID	Unsigned Byte	The ID of the window which was clicked. 0 for player inventory.
			Slot	Short	The clicked slot number, see below
			Button	Byte	The button used in the click, see below
			Action Number	Short	A unique number for the action, implemented by Notchian as a counter, starting at 1. Used by the server to send back a Confirm Transaction.
			Mode	Byte Enum	Inventory operation mode, see below
			Clicked item	Slot	The clicked slot. Has to be empty (item ID = -1) for drop mode.

See Inventory 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 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) (* Clicked item is different, see above)
	1	Normal*	Ctrl + Drop key (Ctrl-Q) (drops full stack)
	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 item), then holding mouse button (left, right or middle) and dragging held 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.

The server will send back a Confirm Transaction packet. If the click was not accepted, the client must reflect that packet before sending more Click Window packets, otherwise the server will reject them silently. The Notchian server also sends a Window Items packet for the open window and Set Slot packets for the clicked and cursor slot, but only when the click was not accepted, probably to resynchronize client and server.

Confirm Transaction

<SpaceManiac> noooo idea why the serverbound confirm transaction packet exists
<SpaceManiac> I think it's sent as a response to the clientbound confirm transaction in some situations, but it's fuzzy

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F 0x10	Play	Server	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	Boolean	Whether the action was accepted

Creative Inventory Action

While the user is in the standard inventory (i.e., not a crafting bench) in Creative mode, the player will send this packet.

Clicking in the creative inventory menu is quite different from non-creative inventory management. Picking up an item with the mouse actually deletes the item from the server, and placing an item into a slot or dropping it out of the inventory actually tells the server to create the item from scratch. (This can be verified by clicking an item that you don't mind deleting, then severing the connection to the server; the item will be nowhere to be found when you log back in.) As a result of this implementation strategy, the "Destroy Item" slot is just a client-side implementation detail that means "I don't intend to recreate this item.". Additionally, the long listings of items (by category, etc.) are a client-side interface for choosing which item to create. Picking up an item from such listings sends no packets to the server; only when you put it somewhere does it tell the server to create the item in that location.

This action can be described as “set inventory slot”. Picking up an item sets the slot to item ID -1. Placing an item into an inventory slot sets the slot to the specified item. Dropping an item (by clicking outside the window) effectively sets slot -1 to the specified item, which causes the server to spawn the item entity, etc.. All other inventory slots are numbered the same as the non-creative inventory (including slots for the 2×2 crafting menu, even though they aren't visible in the vanilla client).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x10 0x11	Play	Server	Slot	Short	Inventory slot
			Clicked Item	Slot

Enchant Item

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x11 0x12	Play	Server	Window ID	Byte	The ID of the enchantment table window 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

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x12 0x13	Play	Server	Location	Position	Block Coordinates
			Line 1	Chat String	First line of text in the sign
			Line 2	Chat String	Second line of text in the sign
			Line 3	Chat String	Third line of text in the sign
			Line 4	Chat String	Fourth line of text in the sign

Player Abilities

The latter 2 bytes are used to indicate the walking and flying speeds respectively, while the first byte is used to determine the value of 4 booleans.

The vanilla client sends this packet when the player starts/stops flying with the second parameter changed accordingly. All other parameters are ignored by the vanilla server.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x13 0x14	Play	Server	Flags	Byte	Bit mask. 0x08: damage disabled (god mode), 0x04: can fly, 0x02: is flying, 0x01: is Creative
			Flying Speed	Float
			Walking Speed	Float

Tab-Complete

Sent when the user presses tab while writing text.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14 0x15	Play	Server	Text	String	All text behind the cursor
			Has Position	Boolean
			Looked At Block	Optional Position	The position of the block being looked at. Only sent if Has Position is true.

Client Settings

Sent when the player connects, or when settings are changed.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15 0x16	Play	Server	Locale	String	e.g. en_GB
			View Distance	Byte	Client-side render distance, in chunks
			Chat Mode	Byte VarInt Enum	0: enabled, 1: commands only, 2: hidden
			Chat Colors	Boolean	“Colors” multiplayer setting
			Displayed Skin Parts	Unsigned Byte	Skin parts, see note below
			Main Hand	VarInt Enum	0: Left, 1: Right

Displayed Skin Parts flags:

• Bit 0 (0x01): Cape enabled
• Bit 1 (0x02): Jacket enabled
• Bit 2 (0x04): Left Sleeve enabled
• Bit 3 (0x08): Right Sleeve enabled
• Bit 4 (0x10): Left Pants Leg enabled
• Bit 5 (0x20): Right Pants Leg enabled
• Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Client Status

Sent when the client is ready to complete login and when the client is ready to respawn after death.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x16 0x17	Play	Server	Action ID	VarInt Enum	See below

Action ID values:

Action ID	Action
0	Perform respawn
1	Request stats
2	Taking Inventory achievement Open Inventory

Plugin Message

Mods and plugins can use this to send their data. Minecraft itself uses a number of plugin channels. These internal channels are prefixed with MC|.

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

Note that the length of Data is known from the packet length, so there is no need for a length field of any kind.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x17 0x18	Play	Server	Channel	String	Name of the plugin channel used to send the data
			Data	Byte Array	Any data, depending on the channel. MC| channels are documented here.

Spectate

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x18 0x19	Play	Server	Target Player	UUID

Resource Pack Status

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x19 0x1A	Play	Server	Hash	String	The hash sent in the Resource Pack Send packet.
			Result	VarInt Enum	0: successfully loaded, 1: declined, 2: failed download, 3: accepted

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.