Protocol

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This page presents a dissection of the current stable Minecraft protocol. The current pre-release protocol is documented elsewhere. The protocol for Pocket Minecraft is substantially different, and is documented at Pocket Minecraft Protocol.

If you're having trouble, check out the FAQ or ask for help in the IRC channel (#mcdevs on irc.freenode.net).

Note: While you may use the contents of this page without restriction to create servers, clients, bots, etc… you still need to provide attribution to #mcdevs if you copy any of the contents of this page for publication elsewhere.

Warning.png As of 1.7 strings are now UTF-8 (prefixed with a VarInt giving the string's length in bytes) instead of UTF-16.

Warning.png As of 1.7.6 all UUIDs used in the protocol now contain '-'. The session server still returns them without

The changes between versions may be viewed at Protocol History

Contents

Definitions

Data types

All data sent over the network (except for VarInt and VarLong) is big-endian, that is the bytes are sent from most significant byte to least significant byte. The majority of everyday computers are little-endian, therefore it may be necessary to change the endianness before sending data over the network.

Name Size (bytes) Encodes Notes
Boolean 1 Either false or true True is encoded as 0x01, false as 0x00.
Byte 1 An integer between -128 and 127 Signed 8-bit integer, two's complement
Unsigned Byte 1 An integer between 0 and 255 Unsigned 8-bit integer
Short 2 An integer between -32768 and 32767 Signed 16-bit integer, two's complement
Unsigned Short 2 An integer between 0 and 65535 Unsigned 16-bit integer
Int 4 An integer between -2147483648 and 2147483647 Signed 32-bit integer, two's complement
Long 8 An integer between -9223372036854775808 and 9223372036854775807 Signed 64-bit integer, two's complement
Float 4 A single-precision 32-bit IEEE 754 floating point number
Double 8 A double-precision 64-bit IEEE 754 floating point number
String (n) ≥ 1
≤ (n×4) + 3 		A sequence of Unicode scalar values UTF-8 string prefixed with its size in bytes as a VarInt. Maximum length of n characters, which varies by context; up to n × 4 bytes can be used to encode n characters and both of those limits are checked. Maximum n value is 32767. The + 3 is due to the max size of a valid length VarInt.
Chat ≥ 1
≤ (32767×4) + 3 		See Chat Encoded as a String with max length of 32767.
Identifier ≥ 1
≤ (32767×4) + 3 		See Identifier below Encoded as a String with max length of 32767.
VarInt ≥ 1
≤ 5 		An integer between -2147483648 and 2147483647 Variable-length data encoding a two's complement signed 32-bit integer; more info in their section
VarLong ≥ 1
≤ 10 		An integer between -9223372036854775808 and 9223372036854775807 Variable-length data encoding a two's complement signed 64-bit integer; more info in their section
Entity Metadata Varies Miscellaneous information about an entity See Entities#Entity Metadata Format
Slot Varies An item stack in an inventory or container See Slot Data
NBT Tag Varies Depends on context See NBT
Position 8 An integer/block position: x (-33554432 to 33554431), y (-2048 to 2047), z (-33554432 to 33554431) x as a 26-bit integer, followed by y as a 12-bit integer, followed by z as a 26-bit integer (all signed, two's complement). See also the section below.
Angle 1 A rotation angle in steps of 1/256 of a full turn Whether or not this is signed does not matter, since the resulting angles are the same.
UUID 16 A UUID Encoded as an unsigned 128-bit integer (or two unsigned 64-bit integers: the most significant 64 bits and then the least significant 64 bits)
Optional X 0 or size of X A field of type X, or nothing Whether or not the field is present must be known from the context.
Array of X count times size of X Zero or more fields of type X The count must be known from the context.
X Enum size of X A specific value from a given list The list of possible values and how each is encoded as an X must be known from the context. An invalid value sent by either side will usually result in the client being disconnected with an error or even crashing.
Byte Array Varies Depends on context This is just a sequence of zero or more bytes, its meaning should be explained somewhere else, e.g. in the packet description. The length must also be known from the context.

Identifier

Identifiers are a namespaced location, in the form of minecraft:thing. If the namespace is not provided, it defaults to minecraft (i.e. thing is minecraft:thing. Custom content should always be in its own namespace, not the default one. The namespace should only use the characters 01​​234​5​6​78​9abcdefghijklmnopqrstuvwxyz-_; actual names may contain more symbols. The naming convention is lower_case_with_underscores. More information.

VarInt and VarLong

Variable-length format such that smaller numbers use fewer bytes. These are very similar to Protocol Buffer Varints: the 7 least significant bits are used to encode the value and the most significant bit indicates whether there's another byte after it for the next part of the number. The least significant group is written first, followed by each of the more significant groups; thus, VarInts are effectively little endian (however, groups are 7 bits, not 8).

VarInts are never longer than 5 bytes, and VarLongs are never longer than 10 bytes.

Pseudocode to read and write VarInts and VarLongs: 

public static int readVarInt() {
    int numRead = 0;
    int result = 0;
    byte read;
    do {
        read = readByte();
        int value = (read & 0b01111111);
        result |= (value << (7 * numRead));

        numRead++;
        if (numRead > 5) {
            throw new RuntimeException("VarInt is too big");
        }
    } while ((read & 0b10000000) != 0);

    return result;
}

public static long readVarLong() {
    int numRead = 0;
    long result = 0;
    byte read;
    do {
        read = readByte();
        int value = (read & 0b01111111);
        result |= (value << (7 * numRead));

        numRead++;
        if (numRead > 10) {
            throw new RuntimeException("VarLong is too big");
        }
    } while ((read & 0b10000000) != 0);

    return result;
}

public static void writeVarInt(int value) {
    do {
        byte temp = (byte)(value & 0b01111111);
        // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
        value >>>= 7;
        if (value != 0) {
            temp |= 0b10000000;
        }
        writeByte(temp);
    } while (value != 0);
}

public static void writeVarLong(long value) {
    do {
        byte temp = (byte)(value & 0b01111111);
        // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
        value >>>= 7;
        if (value != 0) {
            temp |= 0b10000000;
        }
        writeByte(temp);
    } while (value != 0);
}

Warning.png Note that Minecraft's VarInts are not encoded using Protocol Buffers; it's just similar. If you try to use Protocol Buffers Varints with Minecraft's VarInts, you'll get incorrect results in some cases. The major differences:

  • Minecraft's VarInts are all signed, but do not use the ZigZag encoding. Protocol buffers have 3 types of Varints: uint32 (normal encoding, unsigned), sint32 (ZigZag encoding, signed), and int32 (normal encoding, signed). Minecraft's are the int32 variety. Because Minecraft uses the normal encoding instead of ZigZag encoding, negative values always use the maximum number of bytes.
  • Minecraft's VarInts are never be longer than 5 bytes and its VarLongs will never be longer than 10 bytes, while Protocol Buffer Varints will always use 10 bytes when encoding negative numbers, even if it's an int32.

Sample VarInts:

Value Hex bytes Decimal bytes
0 0x00 0
1 0x01 1
2 0x02 2
127 0x7f 127
128 0x80 0x01 128 1
255 0xff 0x01 255 1
2147483647 0xff 0xff 0xff 0xff 0x07 255 255 255 255 7
-1 0xff 0xff 0xff 0xff 0x0f 255 255 255 255 15
-2147483648 0x80 0x80 0x80 0x80 0x08 128 128 128 128 8

Sample VarLongs:

Value Hex bytes Decimal bytes
0 0x00 0
1 0x01 1
2 0x02 2
127 0x7f 127
128 0x80 0x01 128 1
255 0xff 0x01 255 1
2147483647 0xff 0xff 0xff 0xff 0x07 255 255 255 255 7
9223372036854775807 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0x7f 255 255 255 255 255 255 255 255 127
-1 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0x01 255 255 255 255 255 255 255 255 255 1
-2147483648 0x80 0x80 0x80 0x80 0xf8 0xff 0xff 0xff 0xff 0x01 128 128 128 128 248 255 255 255 255 1
-9223372036854775808 0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x01 128 128 128 128 128 128 128 128 128 1

Position

64-bit value split in to three parts

  • x: 26 MSBs
  • z: 26 LSBs
  • y: 12 bits between them

Encoded as followed: 

((x & 0x3FFFFFF) << 38) | ((y & 0xFFF) << 26) | (z & 0x3FFFFFF)

And decoded as: 

val = read_unsigned_long();
x = val >> 38;
y = (val >> 26) & 0xFFF;
z = val << 38 >> 38;

Note: The details of bit shifting are rather language dependent; the above may work in Java but probably won't in other languages without some tweaking. In particular, you will usually receive positive numbers even if the actual coordinates are negative. This can be fixed by adding something like the following: 

if x >= 2^25 { x -= 2^26 }
if y >= 2^11 { y -= 2^12 }
if z >= 2^25 { z -= 2^26 }

Fixed-point numbers

Some fields may be stored as fixed-point numbers, where a certain number of bits represents the signed integer part (number to the left of the decimal point) and the rest represents the fractional part (to the right). Floating points (float and double), in contrast, keep the number itself (mantissa) in one chunk, while the location of the decimal point (exponent) is stored beside it.

Essentially, while fixed-point numbers have lower range than floating points, their fractional precision is greater for higher values. This makes them ideal for representing global coordinates of an entity in Minecraft, as it's more important to store the integer part accurately than position them more precisely within a single block (or meter).

Coordinates are often represented as a 32-bit integer, where 5 of the least-significant bits are dedicated to the fractional part, and the rest store the integer part.

Java lacks support for fractional integers directly, but you can represent them as integers. To convert from a double to this integer representation, use the following formulas: 

 abs_int = (int) (double * 32.0D);

And back again: 

 double = (double) (abs_int / 32.0D);

Particle

Field Name Field Type Meaning
ID VarInt The ID of the particle type, see below.
Data Varies Varies based on the particle type, see below.
Particle Name Particle ID Data
minecraft:ambient_entity_effect 0 None
minecraft:angry_villager 1 None
minecraft:barrier 2 None
minecraft:block 3
Field Name Field Type Meaning
BlockState VarInt The ID of the block state.
minecraft:bubble 4 None
minecraft:cloud 5 None
minecraft:crit 6 None
minecraft:damage_indicator 7 None
minecraft:dragon_breath 8 None
minecraft:dripping_lava 9 None
minecraft:dripping_water 10 None
minecraft:dust 11
Field Name Field Type Meaning
Red Float Red value, 0-1
Green Float Green value, 0-1
Blue Float Blue value, 0-1
Scale Float The scale, will be clamped between 0.01 and 4.
minecraft:effect 12 None
minecraft:elder_guardian 13 None
minecraft:enchanted_hit 14 None
minecraft:enchant 15 None
minecraft:end_rod 16 None
minecraft:entity_effect 17 None
minecraft:explosion_emitter 18 None
minecraft:explosion 19 None
minecraft:falling_dust 20
Field Name Field Type Meaning
BlockState VarInt The ID of the block state.
minecraft:firework 21 None
minecraft:fishing 22 None
minecraft:flame 23 None
minecraft:happy_villager 24 None
minecraft:heart 25 None
minecraft:instant_effect 26 None
minecraft:item 27
Field Name Field Type Meaning
Item Slot The item that will be used.
minecraft:item_slime 28 None
minecraft:item_snowball 29 None
minecraft:large_smoke 30 None
minecraft:lava 31 None
minecraft:mycelium 32 None
minecraft:note 33 None
minecraft:poof 34 None
minecraft:portal 35 None
minecraft:rain 36 None
minecraft:smoke 37 None
minecraft:spit 38 None
minecraft:squid_ink 39 None
minecraft:sweep_attack 40 None
minecraft:totem_of_undying 41 None
minecraft:underwater 42 None
minecraft:splash 43 None
minecraft:witch 44 None
minecraft:bubble_pop 45 None
minecraft:current_down 46 None
minecraft:bubble_column_up 47 None
minecraft:nautilus 48 None
minecraft:dolphin 49 None


Other definitions

Term Definition
Player When used in the singular, Player always refers to the client connected to the server
Entity Entity refers to any item, player, mob, minecart or boat in the world. This definition is subject to change as Notch extends the protocol
EID An EID - or Entity ID - is a unique 4-byte integer used to identify a specific entity
XYZ In this document, the axis names are the same as those shown in the debug screen (F3). Y points upwards, X points East, and Z points South.
See also: Units of Measurement

Packets

Protocol Version

See the Protocol version numbers for details and links to previous versions' documentation.

1.7.2 - 4

1.7.6 - 5

1.8 - 47

Packet format

Field Name Field Type Notes
Length VarInt Length of packet data + length of the packet ID
Packet ID VarInt
Data

Post compression

Once a Set Compression packet is sent, zlib compression is enabled for all following packets. The format of a packet changes slighty to include the size of the uncompressed packet.

Name Type Notes
Packet Length VarInt Length of Data + length of Data Length
Data Length VarInt Length of uncompressed Data or 0
Data zlib compressed packet, including Packet ID

The length given by the Packet Length field is the number of bytes that remain in that packet, including the Data Length field.

If Data Length is set to zero, then the packet is uncompressed; otherwise it is the size of the uncompressed packet.

If compressed, the data's length must be equal to or over the threshold set in the Set Compression packet, otherwise the client/server will disconnect.

Compression can be disabled by sending a threshold of -1.

Handshaking

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Handshake Server Protocol Version VarInt (4 as of 1.7.2)
Server Address (hostname or IP) String localhost
Server Port Unsigned Short 25565
Next state VarInt 1 for status, 2 for login

Play

Clientbound

Keep Alive

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same packet. If the client does not respond to them for over 30 seconds, the server kicks the client. Vice versa, if the server does not send any keep-alives for 20 seconds, the client will disconnect and yields a "Timed out" exception.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Play Client Keep Alive ID VarInt

Join Game

See Protocol Encryption for information on logging in.

Packet ID Category Bound To Field Name Field Type Notes
0x01 Play Client Entity ID Int The player's Entity ID
Gamemode Unsigned 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
Max Players Unsigned Byte Used by the client to draw the player list
Level Type String default, flat, largeBiomes, amplified, default_1_1
Reduced Debug Info Boolean

Warning.png If the Dimension isn't valid then the client will crash

Chat Message

Identifying the difference between Chat/System Message is important as it helps respect the user's chat visibility options. While position 2 accepts json formatting it will not display, old style formatting works

Packet ID Category Bound To Field Name Field Type Notes
0x02 Play Client JSON Data String Chat , Limited to 32767 bytes
Position Byte 0 - Chat (chat box) ,1 - System Message (chat box), 2 - Above action bar

Warning.png Malformed JSON will disconnect the client

Time Update

Time is based on ticks, where 20 ticks happen every second. There are 24000 ticks in a day, making Minecraft days exactly 20 minutes long.

The time of day is based on the timestamp modulo 24000. 0 is sunrise, 6000 is noon, 12000 is sunset, and 18000 is midnight.

The default SMP server increments the time by 20 every second.

Packet ID Category Bound To Field Name Field Type Notes
0x03 Play Client 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 Category Bound To Field Name Field Type Notes
0x04 Play Client EntityID VarInt 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

Sent by the server after login to specify the coordinates of the spawn point (the point at which players spawn at, and which the compass points to). It can be sent at any time to update the point compasses point at.

Packet ID Category Bound To Field Name Field Type Notes
0x05 Play Client Location Position Spawn location

Update Health

Sent by the server to update/set the health of the player it is sent to.

Food saturation acts as a food "overcharge". Food values will not decrease while the saturation is over zero. Players logging in automatically get a saturation of 5.0. Eating food increases the saturation as well as the food bar.

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

Respawn

To change the player's dimension (overworld/nether/end), send them a respawn packet with the appropriate dimension, followed by prechunks/chunks for the new dimension, and finally a position and look packet. You do not need to unload chunks, the client will do it automatically.

Packet ID Category Bound To Field Name Field Type Notes
0x07 Play Client Dimension Int -1: The Nether, 0: The Overworld, 1: The End
Difficulty Unsigned Byte 0 thru 3 for Peaceful, Easy, Normal, Hard.
Gamemode Unsigned Byte 0: survival, 1: creative, 2: adventure. The hardcore flag is not included
Level Type String Same as Join Game

Warning.png If the Dimension isn't valid then the client will crash

Warning.png Avoid changing player's dimension to same dimension they were already in, weird bugs can occur i.e. such player will be unable to attack other players in new world (fixes after their death and respawn)

Player Position And Look

Updates the players position on the server. If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 units will result in the client being kicked for "You moved too quickly :( (Hacking?)" Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for "Illegal position"

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0,-1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw of player (in degrees), standing at point (x0,z0) and looking towards point (x,z) one can be calculated with: 

 l = x-x0
 w = z-z0
 c = sqrt( l*l + w*w )
 alpha1 = -arcsin(l/c)/PI*180
 alpha2 =  arccos(w/c)/PI*180
 if alpha2 > 90 then
   yaw = 180 - alpha1
 else
   yaw = alpha1

You can get a unit vector from a given yaw/pitch via: 

 x = -cos(pitch) * sin(yaw)
 y = -sin(pitch)
 z =  cos(pitch) * cos(yaw)

About the flags field: 

 <Dinnerbone> It's a bitfield, X/Y/Z/Y_ROT/X_ROT. If X is set, the x value is relative and not absolute.
Packet ID Category Bound To Field Name Field Type Notes
0x08 Play Client X Double Absolute/Relative position
Y Double Absolute/Relative position
Z Double Absolute/Relative position
Yaw Float Absolute/Relative rotation on the X Axis, in degrees
Pitch Float Absolute/Relative rotation on the Y Axis, in degrees
Flags Byte
X 0x01
Y 0x02
Z 0x04
Y_ROT 0x08
X_ROT 0x10

Held Item Change

Sent to change the player's slot selection

Packet ID Category Bound To Field Name Field Type Notes
0x09 Play Client Slot Byte The slot which the player has selected (0-8)

Use Bed

This packet tells that a player goes to bed.

The client with the matching Entity ID will go into bed mode.

This Packet is sent to all nearby players including the one sent to bed.

Packet ID Category Bound To Field Name Field Type Notes
0x0A Play Client Entity ID VarInt Player ID
Location Position Block location of the head part of the bed

Animation

Sent whenever an entity should change animation.

Packet ID Category Bound To Field Name Field Type Notes
0x0B Play Client Entity ID VarInt Player ID
Animation Unsigned Byte Animation ID

Animation can be one of the following values:

ID Animation
0 Swing arm
1 Damage animation
2 Leave bed
3 Eat food
4 Critical effect
5 Magic critical effect
102 (unknown)
104 Crouch
105 Uncrouch

Spawn Player

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

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 :)
Packet ID Category Bound To Field Name Field Type Notes
0x0C Play Client Entity ID VarInt Player's Entity ID
Player UUID UUID Player's UUID
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

Warning.png The client will crash if no metadata is sent

Collect Item

Sent by the server when someone picks up an item lying on the ground - its sole purpose appears to be the animation of the item flying towards you. It doesn't destroy the entity in the client memory, and it doesn't add it to your inventory. The server only checks for items to be picked up after each Player Position [and Player Position & Look] packet sent by the client.

Packet ID Category Bound To Field Name Field Type Notes
0x0D Play Client Collected Entity ID VarInt
Collector Entity ID VarInt

Spawn Object

Sent by the server when an Object/Vehicle is created.

Packet ID Category Bound To Field Name Field Type Notes
0x0E Play Client Entity ID VarInt Entity ID of the object
Type Byte The type 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

Sent by the server when a Mob Entity is Spawned

Packet ID Category Bound To Field Name Field Type Notes
0x0F Play Client Entity ID VarInt 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
Yaw Byte The yaw in steps of 2p/256
Pitch Byte The pitch in steps of 2p/256
Head Pitch Byte The pitch in steps of 2p/256
Velocity X Short
Velocity Y Short
Velocity Z Short
Metadata Metadata

Spawn Painting

This packet shows location, name, and type of painting.

Calculating the center of an image: given a (width x height) grid of cells, with (0, 0) being the top left corner, the center is (max(0, width / 2 - 1), height / 2). E.g.

2x1 (1, 0) 4x4 (1, 2)


Packet ID Category Bound To Field Name Field Type Notes
0x10 Play Client Entity ID VarInt Entity's ID
Title String Name of the painting. Max length 13
Location Position Center coordinates
Direction Unsigned Byte Direction the painting faces (0 -z, 1 -x, 2 +z, 3 +x)

Spawn Experience Orb

Spawns one or more experience orbs.

Packet ID Category Bound To Field Name Field Type Notes
0x11 Play Client Entity ID VarInt 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

Velocity is believed to be in units of 1/8000 of a block per server tick (50ms); for example, -1343 would move (-1343 / 8000) = −0.167875 blocks per tick (or −3,3575 blocks per second).

Packet ID Category Bound To Field Name Field Type Notes
0x12 Play Client Entity ID VarInt 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 Entities

Sent by the server when an list of Entities is to be destroyed on the client.

Packet ID Category Bound To Field Name Field Type Notes
0x13 Play Client Count VarInt Length of following array
Entity IDs Array of VarInt The list of entities of destroy

Entity

Most entity-related packets are subclasses of this packet. When sent from the server to the client, it may initialize the entry.

For player entities, either this packet or any move/look packet is sent every game tick. So the meaning of this packet is basically that the entity did not move/look since the last such packet.

Packet ID Category Bound To Field Name Field Type Notes
0x14 Play Client Entity ID VarInt Entity's ID

Entity Relative Move

This packet is sent by the server when an entity moves less then 4 blocks; if an entity moves more than 4 blocks Entity Teleport should be sent instead.

This packet allows at most four blocks movement in any direction, because byte range is from -128 to 127.

Packet ID Category Bound To Field Name Field Type Notes
0x15 Play Client Entity ID VarInt 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
On Ground Boolean

Entity Look

This packet is sent by the server when an entity rotates. Example: "Yaw" field 64 means a 90 degree turn.

Packet ID Category Bound To Field Name Field Type Notes
0x16 Play Client Entity ID VarInt 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
On Ground Boolean

Entity Look and Relative Move

This packet is sent by the server when an entity rotates and moves. Since a byte range is limited from -128 to 127, and movement is offset of fixed-point numbers, this packet allows at most four blocks movement in any direction. (-128/32 == -4)

Packet ID Category Bound To Field Name Field Type Notes
0x17 Play Client Entity ID VarInt 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
On Ground Boolean

Entity Teleport

This packet is sent by the server when an entity moves more than 4 blocks.

Packet ID Category Bound To Field Name Field Type Notes
0x18 Play Client Entity ID VarInt 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
Yaw Byte The X Axis rotation as a fraction of 360
Pitch Byte The Y Axis rotation as a fraction of 360
On Ground Boolean

Entity Head Look

Changes the direction an entity's head is facing.

Packet ID Category Bound To Field Name Field Type Notes
0x19 Play Client Entity ID VarInt Entity's ID
Head Yaw Byte Head yaw in steps of 2p/256

Entity Status

Packet ID Category Bound To Field Name Field Type Notes
0x1A Play Client Entity ID Int Entity's ID
Entity Status Byte See below
Entity Status Meaning
0 Something related to living entities?
1 Something related to the player entity?
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
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 Zombie converting into a villager by shaking violently
17 Firework exploding
18 Animal in love (ready to mate) - Spawn "heart" particles

Attach Entity

This packet is sent when a player has been attached to an entity (e.g. Minecart)

Packet ID Category Bound To Field Name Field Type Notes
0x1B Play Client Entity ID Int Entity's ID
Vehicle ID Int Vechicle's Entity ID
Leash Bool If true leashes the entity to the vehicle

Entity Metadata

Packet ID Category Bound To Field Name Field Type Notes
0x1C Play Client Entity ID VarInt Entity's ID
Metadata Metadata

Entity Effect

Packet ID Category Bound To Field Name Field Type Notes
0x1D Play Client Entity ID VarInt Entity's ID
Effect ID Byte See [[1]]
Amplifier Byte
Duration VarInt
Hide Particles Boolean

Remove Entity Effect

Packet ID Category Bound To Field Name Field Type Notes
0x1E Play Client Entity ID VarInt Entity's ID
Effect ID Byte

Set Experience

Sent by the server when the client should change experience levels.

Packet ID Category Bound To Field Name Field Type Notes
0x1F Play Client Experience bar Float Between 0 and 1
Level VarInt
Total Experience VarInt

Entity Properties

Packet ID Category Bound To Field Name Field Type Notes
0x20 Play Client Entity ID VarInt 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 VarInt 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

Chunks are not unloaded by the client automatically. To unload chunks, send this packet with ground-up continuous=true and no 16^3 chunks (eg. primary bit mask=0). The server does not send skylight information for nether-chunks, it's up to the client to know if the player is currently in the nether. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent.

See also: SMP Map Format

Changes in 1.8:

  • Data value section removed
  • Extended id section removed
  • Block id section is now a unsigned short (little endian) per a block
  • The block id is equal to (id << 4) | data
Packet ID Category 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 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.
Size VarInt Size of chunk data
Data Byte array The chunk data is not compressed as of 14w28a

Multi Block Change

Packet ID Category Bound To Field Name Field Type Notes
0x22 Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z Coordinate
Record count VarInt The number of blocks affected
Records Array of Records

Record

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

Block Change

Packet ID Category Bound To Field Name Field Type Notes
0x23 Play Client Location Position Block Coordinates
Block ID VarInt The new block ID for the block. id << 4 | data

Block Action

This packet is used for a number of things:

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

See Also: Block Actions

Packet ID Category Bound To Field Name Field Type Notes
0x24 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 The block type for the block


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. (Water will lose it's transparency)

Packet ID Category Bound To Field Name Field Type Notes
0x25 Play Client Entity ID VarInt Entity's ID
Location Position Block Position
Destroy Stage Byte 0 - 9

Map Chunk Bulk

See also: SMP Map Format

1.8 changes at #Chunk_Data

To reduce the number of bytes this packet is used to send chunks together for better compression results.

Packet ID Category Bound To Field Name Field Type Notes
0x26 Play Client 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
Chunk column count VarInt The number of chunk in this packet
Meta information Meta See below
Data Byte Array Chunk data. Uncompressed as of 14w28a

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

Explosion

Sent when an explosion occurs (creepers, TNT, and ghast fireballs).

Each block in Records is set to air. Coordinates for each axis in record is int(X) + record.x

Packet ID Category Bound To Field Name Field Type Notes
0x27 Play Client X Float
Y Float
Z Float
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

Sent when a client is to play a sound or particle effect.

By default, the minecraft client adjusts the volume of sound effects based on distance. The final boolean field is used to disable this, and instead the effect is played from 2 blocks away in the correct direction. Currently this is only used for effect 1013 (mob.wither.spawn), and is ignored for any other value by the client.

Packet ID Category Bound To Field Name Field Type Notes
0x28 Play Client Effect ID Int The ID of the effect, see below.
Location Position The location of the effect
Data Int Extra data for certain effects, see below.
Disable relative volume Bool See above
Effects
ID Name
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 (green crosses), used for bonemealing vegetation.

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

Used to play a sound effect on the client.

All known sound effect names can be seen here.

Custom sounds may be added by resource packs

Packet ID Category Bound To Field Name Field Type Notes
0x29 Play Client 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 Unsigned Byte 63 is 100%, can be more

Particle

Displays the named particle

Packet ID Category Bound To Field Name Field Type Notes
0x2A Play Client Particle Id Int
Long Distance Boolean If true, particle distance increases from 256 to 65536.
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 data Float The data of each particle
Number of particles Int The number of particles to create
Data Array of VarInt Length depends on particle. ICON_CRACK, BLOCK_CRACK, and BLOCK_DUST have lengths of 2, the rest have 0.

Particle Ids

Particle Name Particle Id
explode 0
largeexplosion 1
hugeexplosion 2
fireworksSpark 3
bubble 4
wake 5
splash 6
suspended 7
townaura 8
crit 9
magicCrit 10
smoke 11
largesmoke 12
mobSpell? 13
instantSpell 14
spell 15
witchMagic 17
dripWater 18
dripLava 19
angryVillager 20
happyVillager 21
depthsuspend 22
note 23
portal 24
enchantmenttable 25
flame 26
lava 27
footstep 28
cloud 29
reddust 30
snowballpoof 31
snowshovel 32
slime 33
heart 34
barrier 35

Change Game State

It appears when a bed can't be used as a spawn point and when the rain state changes.

The class has an array of strings linked to reason codes 0, 1, 2, and 3 but only the codes for 1 and 2 are null.

Packet ID Category Bound To Field Name Field Type Notes
0x2B Play Client Reason Unsigned Byte
Value Float Depends on reason

Reason codes

Code Effect Notes
0 Invalid Bed "tile.bed.notValid"
1 End raining
2 Begin 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
6 Arrow hitting player Appears to be played when an arrow strikes another player in Multiplayer
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

With this packet, the server notifies the client of thunderbolts striking within a 512 block radius around the player. The coordinates specify where exactly the thunderbolt strikes.

Packet ID Category Bound To Field Name Field Type Notes
0x2C Play Client Entity ID VarInt 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

This is sent to the client when it should open an inventory, such as a chest, workbench, or furnace. This message is not sent anywhere for clients opening their own inventory.

Packet ID Category Bound To Field Name Field Type Notes
0x2D Play Client Window id Unsigned Byte A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
Inventory Type String The window type to use for display. Check below
Window title Chat The title of the window.
Number of Slots Unsigned Byte Number of slots in the window (excluding the number of slots in the player inventory).
Entity ID Int EntityHorse's entityId. Only sent when window type is equal to "EntityHorse".

See inventory windows for further information.

Close Window

This packet is sent from the server to the client when a window is forcibly closed, such as when a chest is destroyed while it's open.

Note, notchian clients send a close window message with window id 0 to close their inventory even though there is never an Open Window message for inventory.

Packet ID Category Bound To Field Name Field Type Notes
0x2E Play Client Window ID Unsigned Byte This is the id of the window that was closed. 0 for inventory.

Set Slot

Sent by the server when an item in a slot (in a window) is added/removed.

Packet ID Category Bound To Field Name Field Type Notes
0x2F Play Client 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

The inventory slots

Sent by the server when an item in a slot (in a window) is added/removed. This includes the main inventory, equipped armour and crafting slots.

Packet ID Category Bound To Field Name Field Type Notes
0x30 Play Client Window ID Unsigned 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 Category Bound To Field Name Field Type Notes
0x31 Play Client Window ID Unsigned 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.

Beacon

  • 0: Power level
  • 1: Potion effect one
  • 2: Potion effect two

Anvil

  • 0: Maximum cost

Brewing Stand

  • 0: Brew time

Brew time is a value between 0 and 400, with 400 making the arrow empty, and 0 making the arrow full.

Confirm Transaction

A packet from the server indicating whether a request from the client was accepted, or whether there was a conflict (due to lag). This packet is also sent from the client to the server in response to a server transaction rejection packet.

Packet ID Category Bound To Field Name Field Type Notes
0x32 Play Client Window ID Unsigned 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

This message is sent from the server to the client whenever a sign is discovered or created. This message is NOT sent when a sign is destroyed or unloaded.

Packet ID Category Bound To Field Name Field Type Notes
0x33 Play Client Location Position Block Coordinates
Line 1 Chat First line of text in the sign
Line 2 Chat Second line of text in the sign
Line 3 Chat Third line of text in the sign
Line 4 Chat Fourth line of text in the sign

Maps

Packet ID Category Bound To Field Name Field Type Notes
0x34 Play Client Item Damage VarInt The damage value of the map being modified
Scale Byte
Length VarInt
Icons 3 * length bytes First byte, 0xF0 = Direction, 0x0F = Type. Second byte, X. Third byte, Y
Columns Byte
Rows Byte Only if Columns is more than 0
X Byte Only if Columns is more than 0
Y Byte Only if Columns is more than 0
Length VarInt Only if Columns is more than 0
Data Length bytes Only if Columns is more than 0

Update Block Entity

Essentially a block update on a block entity.

Packet ID Category Bound To Field Name Field Type Notes
0x35 Play Client Location Position
Action Unsigned Byte The type of update to perform
NBT Data Byte Array If not present then its TAG_END (0)

Actions

  • 1: Set SpawnPotentials of a mob spawner
  • 2: Set command block text (command and last execution status)
  • 3: Set the level, primary, and secondary powers of a beacon
  • 4: Set rotation and skin of mob head
  • 5: Set type of flower in flower pot
  • 6: Set base color and patterns on a banner

Sign Editor Open

Sent on placement of sign.

Packet ID Category Bound To Field Name Field Type Notes
0x36 Play Client Location Position Block coordinates

Statistics

Packet ID Category Bound To Field Name Field Type Notes
0x37 Play Client Count VarInt Number of entries
Entry Statistic's name String https://gist.github.com/thinkofdeath/a1842c21a0cf2e1fb5e0
Value VarInt The amount to set it to

Player List Item

Sent by the notchian server to update the user list (<tab> in the client).

Packet ID Category Bound To Field Name Field Type Notes
0x38 Play Client Action VarInt
Length VarInt The following fields are repeated length times
UUID UUID The uuid of the player
Action
0 (ADD_PLAYER) Name String
Number of properties VarInt
Properties Name String
Value String
Is Signed Boolean
Signature String Only if Is Signed is true
Gamemode VarInt
Ping VarInt
Has Display Name Boolean
Display Name Chat Only send if Has Diplay Name is true
1 (UPDATE_GAMEMODE) Gamemode VarInt
2 (UPDATE_LATENCY) Ping VarInt
3 (UPDATE_DISPLAY_NAME) Has Display Name Boolean
Display Name Chat Only send if Has Diplay Name is true
4 (REMOVE_PLAYER)

Player Abilities

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

The flags are whether damage is disabled (god mode, 8, bit 3), whether the player can fly (4, bit 2), whether the player is flying (2, bit 1), and whether the player is in creative mode (1, bit 0).

To get the values of these booleans, simply AND (&) the byte with 1,2,4 and 8 respectively, to get the 0 or 1 bitwise value. To set them OR (|) them with their repspective masks.

Packet ID Category Bound To Field Name Field Type Notes
0x39 Play Client Flags Byte
Flying speed Float previous integer value divided by 250
Walking speed Float previous integer value divided by 250

Tab-Complete

The server responds with a list of auto-completions of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported.

Packet ID Category Bound To Field Name Field Type Notes
0x3A Play Client Count VarInt Number of following strings
Match String One eligible command, note that each command is sent separately instead of in a single string, hence the need for Count

Scoreboard Objective

This is sent to the client when it should create a new scoreboard or remove one.

Packet ID Category Bound To Field Name Field Type Notes
0x3B Play Client Objective name String An unique name for the objective
Mode Byte 0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.
Objective value String Only if mode is 0 or 2. The text to be displayed for the score.
Type String Only if mode is 0 or 2. "integer" or "hearts"

Update Score

This is sent to the client when it should update a scoreboard item.

Packet ID Category Bound To Field Name Field Type Notes
0x3C Play Client Score name String The name of the score to be updated or removed.
Update/Remove Byte 0 to create/update an item. 1 to remove an item.
Objective Name String The name of the objective the score belongs to.
Value VarInt The score to be displayed next to the entry. Only sent when Update/Remove does not equal 1.

Display Scoreboard

This is sent to the client when it should display a scoreboard.

Packet ID Category Bound To Field Name Field Type Notes
0x3D Play Client 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

Creates and updates teams.

Packet ID Category Bound To Field Name Field Type Notes
0x3E Play Client 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
Name Tag Visibility String Only if Mode = 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
Color Byte Only if Mode = 0 or 2. Same as Chat colors.
Player count VarInt 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. Max 40 characters so may be uuid's later

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/

Packet ID Category Bound To Field Name Field Type Notes
0x3F Play Client Channel String Name of the "channel" used to send the data.
Data Byte Array Any data.

Disconnect

Sent by the server before it disconnects a client. The server assumes that the sender has already closed the connection by the time the packet arrives.

Packet ID Category Bound To Field Name Field Type Notes
0x40 Play Client Reason String Displayed to the client when the connection terminates. Must be valid JSON.

Server Difficulty

Changes the difficulty setting in the client's option menu

Packet ID Category Bound To Field Name Field Type Notes
0x41 Play Client Difficulty Unsigned Byte 0:PEACEFUL, 1:EASY, 2:NORMAL, 3: HARD


Combat Event

Packet ID Category Bound To Field Name Field Type Notes
0x42 Play Client Event VarInt 0 ENTER_COMBAT, 1 END_COMBAT, 2 ENTITY_DEAD
Duration VarInt Only for END_COMBAT
Entity ID Int Only for END_COMBAT
Player ID VarInt Only for ENTITY_DEAD
Entity ID Int Only for ENTITY_DEAD
Message String Only for ENTITY_DEAD

Camera

Packet ID Category Bound To Field Name Field Type Notes
0x43 Play Client Camera ID VarInt

World Border

Packet ID Category Bound To Field Name Field Type Notes
0x44 Play Client Action VarInt
Action Name
0 (SET_SIZE) Radius Double
1 (LERP_SIZE) Old radius Double
New radius Double
Speed VarLong
2 (SET_CENTER) X Double
Z Double
3 (INITIALIZE) X Double
Z Double
Old radius Double
New radius Double
Speed VarLong
Portal Teleport Boundary VarInt Resulting coordinates from a portal teleport are limited to +-value. Usually 29999984.
Warning time VarInt
Warning blocks VarInt
4 (SET_WARNING_TIME) Warning time VarInt
5 (SET_WARNING_BLOCKS) Warning blocks VarInt

Title

Packet ID Category Bound To Field Name Field Type Notes
0x45 Play Client Action VarInt
Action Name
0 (TITLE) Text Chat
1 (SUBTITLE) Text Chat
2 (TIMES) Fade In Int
Stay Int
Fade Out Int
3 (CLEAR)
4 (RESET)

Set Compression

Packet ID Category Bound To Field Name Field Type Notes
0x46 Play Client Threshold VarInt Threshold is the max size of a packet before its compressed

Player List Header/Footer

Packet ID Category Bound To Field Name Field Type Notes
0x47 Play Client Header Chat
Footer Chat

Resource Pack Send

Packet ID Category Bound To Field Name Field Type Notes
0x48 Play Client URL String
Hash String If it's not a 40 character hexadecimal string, the client will not use it for hash verification and likely waste bandwidth - but it will still treat it as a unique id

Update Entity NBT

Packet ID Category Bound To Field Name Field Type Notes
0x49 Play Client Entity ID VarInt
Tag NBT Tag

Serverbound

Keep Alive

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same packet.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Play Server Keep Alive ID VarInt

Chat Message

The default server will check the message to see if it begins with a '/'. If it doesn't, the username of the sender is prepended and sent to all other clients (including the original sender). If it does, the server assumes it to be a command and attempts to process it. A message longer than 100 characters will cause the server to kick the client. This change was initially done by allowing the client to not slice the message up to 119 (the previous limit), without changes to the server. For this reason, the vanilla server kept the code to cut messages at 119, but this isn't a protocol limitation and can be ignored.

For more information, see Chat.

Packet ID Category Bound To Field Name Field Type Notes
0x01 Play Server Message String

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 Category Bound To Field Name Field Type Notes
0x02 Play Server Target VarInt
Type VarInt 0 = INTERACT, 1 = ATTACK, 2 = INTERACT_AT
Target X Float Only if Type == INTERACT_AT
Target Y Float Only if Type == INTERACT_AT
Target Z Float Only if Type == INTERACT_AT

Player

This packet is used to indicate whether the player is on ground (walking/swimming), or airborne (jumping/falling).

When dropping from sufficient height, fall damage is applied when this state goes from False to True. The amount of damage applied is based on the point where it last changed from True to False. Note that there are several movement related packets containing this state.

Packet ID Category Bound To Field Name Field Type Notes
0x03 Play Server On Ground Bool True if the client is on the ground, False otherwise

Player Position

Updates the players XYZ position on the server. If HeadY - FeetY is less than 0.1 or greater than 1.65, the stance is illegal and the client will be kicked with the message “Illegal Stance”. If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 units will result in the client being kicked for "You moved too quickly :( (Hacking?)" Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for "Illegal position"

Packet ID Category Bound To Field Name Field Type Notes
0x04 Play Server X Double Absolute position
FeetY Double Absolute feet position, normally HeadY - 1.62. 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

The unit circle for yaw
The unit circle of yaw, redrawn

Updates the direction the player is looking in.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0,-1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw of player (in degrees), standing at point (x0,z0) and looking towards point (x,z) one can be calculated with: 

 l = x-x0
 w = z-z0
 c = sqrt( l*l + w*w )
 alpha1 = -arcsin(l/c)/PI*180
 alpha2 =  arccos(w/c)/PI*180
 if alpha2 > 90 then
   yaw = 180 - alpha1
 else
   yaw = alpha1

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

You can get a unit vector from a given yaw/pitch via: 

 x = -cos(pitch) * sin(yaw)
 y = -sin(pitch)
 z =  cos(pitch) * cos(yaw)
Packet ID Category Bound To Field Name Field Type Notes
0x05 Play Server 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

A combination of Player Look and Player position.

Packet ID Category Bound To Field Name Field Type Notes
0x06 Play Server X Double Absolute position
FeetY Double Absolute feet position. Is normally HeadY - 1.62. 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

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

Status can (currently) be one of six values:

Meaning Value
Started digging 0
Cancelled digging 1
Finished digging 2
Drop item stack 3
Drop item 4
Shoot arrow / finish eating 5

Notchian clients send a 0 (started digging) when they start digging and a 2 (finished digging) once they think they are finished. If digging is aborted, the client simply send a 1 (Cancel digging).

Status code 4 (drop item) is a special case. In-game, when you use the Drop Item command (keypress 'q'), a dig packet with a status of 4, and all other values set to 0, is sent from client to server. Status code 3 is similar, but drops the entire stack.

Status code 5 (shoot arrow / finish eating) is also a special case. The x, y and z fields are all set to 0 like above, with the exception of the face field, which is set to 255.

The face can be one of six values, representing the face being hit:

Value 0 1 2 3 4 5
Offset -Y +Y -Z +Z -X +X

In 1.7.3, when a player opens a door with left click the server receives Packet 0xE+start digging and opens the door.

Player Block Placement

Packet ID Category Bound To Field Name Field Type Notes
0x08 Play Server Location Position 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, pulling back 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

Sent when the player changes the slot selection

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

Animation

Packet ID Category Bound To Field Name Field Type Notes
0x0A Play Server

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 Category Bound To Field Name Field Type Notes
0x0B Play Server Entity ID VarInt Player ID
Action ID Unsigned Byte The ID of the action, see below.
Jump Boost VarInt Horse jump boost. Ranged from 0 -> 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

Steer Vehicle

Packet ID Category Bound To Field Name Field Type Notes
0x0C Play Server Sideways Float Positive to the left of the player
Forward Float Positive forward
Flags Unsigned Byte 0x1 Jump, 0x2 Unmount

Close Window

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

Note, notchian clients send a close window message with window id 0 to close their inventory even though there is never an Open Window message for inventory.

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


Click Window

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

Packet ID Category Bound To Field Name Field Type Notes
0x0E Play Server 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 Category Bound To Field Name Field Type Notes
0x0F 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 Bool Whether the action was accepted.

Creative Inventory Action

While the user is in the standard inventory (i.e., not a crafting bench) on a creative-mode server then the server will send this packet:

  • If an item is dropped into the quick bar
  • If an item is picked up from the quick bar (item id is -1)
Packet ID Category Bound To Field Name Field Type Notes
0x10 Play Server Slot Short Inventory slot
Clicked item Slot

Enchant Item

Packet ID Category Bound To Field Name Field Type Notes
0x11 Play Server 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

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

Packet ID Category Bound To Field Name Field Type Notes
0x12 Play Server Location Position Block Coordinates
Line 1 Chat First line of text in the sign
Line 2 Chat Second line of text in the sign
Line 3 Chat Third line of text in the sign
Line 4 Chat 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 flags are whether damage is disabled (god mode, 8, bit 3), whether the player can fly (4, bit 2), whether the player is flying (2, bit 1), and whether the player is in creative mode (1, bit 0).

To get the values of these booleans, simply AND (&) the byte with 1,2,4 and 8 respectively, to get the 0 or 1 bitwise value. To set them OR (|) them with their repspective masks. 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 Category Bound To Field Name Field Type Notes
0x13 Play Server Flags Byte
Flying speed Float previous integer value divided by 250
Walking speed Float previous integer value divided by 250

Tab-Complete

Sent when the user presses [tab] while writing text. The payload contains all text behind the cursor.

Packet ID Category Bound To Field Name Field Type Notes
0x14 Play Server Text String
Has Position Boolean
Looked at block Position The position of the block being looked at. Only sent if the previous field is true

Client Settings

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

Packet ID Category Bound To Field Name Field Type Notes
0x15 Play Server Locale String en_GB
View distance Byte Client-side render distance(chunks)
Chat flags Byte Chat settings. See notes below.
Chat colours Bool "Colours" multiplayer setting
Displayed skin parts Unsigned Byte Skin parts. See note below

Chat flags has several values packed into one byte.

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

Displayed skin parts also packs several values into one byte.

Bit 0: Cape enabled

Bit 1: Jacket enabled

Bit 2: Left Sleeve enabled

Bit 3: Right Sleeve enabled

Bit 4: Left Pants Leg enabled

Bit 5: Right Pants Leg enabled

Bit 6: Hat enabled

The most significant bit (bit 7) 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 Category Bound To Field Name Field Type Notes
0x16 Play Server Action ID Unsigned Byte See below

Action ID values:

Action ID Name
0 Perform respawn
1 Request stats
2 Open inventory achievement

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 data length is known from the packet length, so there is no need for a length member being sent. However, Minecraft sends the length within the payload. BungeeCord, on the other hand, doesn't send the payload length.

Packet ID Category Bound To Field Name Field Type Notes
0x17 Play Server Channel String Name of the "channel" used to send the data.
Data Byte Array Any data.

Spectate

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

Resource Pack Status

Packet ID Category Bound To Field Name Field Type Notes
0x19 Play Server Hash String
Result VarInt Successfully loaded: 0, Declined: 1, Failed download: 2, Accepted: 3

Status

The status ping works as follows. 

   C->S : Handshake State=1
   C->S : Request
   S->C : Response
   C->S : Ping
   S->C : Ping

Clientbound

Response

Packet ID Category Bound To Field Name Field Type Notes
0x00 Status Client JSON Response String https://gist.github.com/thinkofdeath/6927216


Ping

Packet ID Category Bound To Field Name Field Type Notes
0x01 Status Client Time Long Should be the same as sent by the client

Serverbound

Request

Packet ID Category Bound To Field Name Field Type Notes
0x00 Status Server


Ping

Packet ID Category Bound To Field Name Field Type Notes
0x01 Status Server Time Long

Login

The login process is as follows: 

   C->S : Handshake State=2
   C->S : Login Start
   S->C : Encryption Key Request
   (Client Auth)
   C->S : Encryption Key Response
   (Server Auth, Both enable encryption)
   S->C : Login Success

For unauthenticated and* localhost connections there is no encryption. In that case Login Start is directly followed by Login Success.

* It could be that only one of the two conditions is enough for an unencrypted connection.

See Protocol Encryption for details.

Clientbound

Disconnect

Packet ID Category Bound To Field Name Field Type Notes
0x00 Login Client JSON Data String

Encryption Request

Packet ID Category Bound To Field Name Field Type Notes
0x01 Login Client Server ID String appears to be empty as of 1.7.x
Length VarInt length of public key
Public Key Byte array
Length VarInt length of verify token
Verify Token Byte array

See Protocol Encryption for details.

Login Success

Packet ID Category Bound To Field Name Field Type Notes
0x02 Login Client UUID String
Username String

Set Compression

Packet ID Category Bound To Field Name Field Type Notes
0x03 Login Client Threshold VarInt Threshold is the max size of a packet before its compressed

Serverbound

Login Start

Packet ID Category Bound To Field Name Field Type Notes
0x00 Login Server Name String

Encryption Response

Packet ID Category Bound To Field Name Field Type Notes
0x01 Login Server Length VarInt length of shared secret
Shared Secret Byte array
Length VarInt length of verify token
Verify Token Byte array

See Protocol Encryption for details.

See Also

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