Minecraft:Java Edition protocol/Chat

This article details various aspects of Minecraft's chat system. The packets themselves are documented in Minecraft:Java Edition protocol/Packets.

Client chat mode

The client may use the Chat Mode field of the Client Information packet to indicate that it only wants to receive some types of chat messages.

It is the server's responsibility to not send packets if the client has the given type disabled. However, it is the client's responsibility to not send incorrect chat packets.

Here's a matrix comparing what packets the server should send to clients based on their chat settings:

Clientbound packet	Client setting			Usage
	Full	Commands only	Hidden
Player Chat Message	Template:Tc	Template:Tc	Template:Tc	Player-initiated chat messages, including the commands /say, /me, /msg, /tell, /w and /teammsg.
Disguised Chat Message	Template:Tc	Template:Tc	Template:Tc	Messages sent by non-players using the commands /say, /me, /msg, /tell, /w and /teammsg.
System Chat Message	Template:Tc	Template:Tc	Template:Tc	Feedback from running a command, such as "Your game mode has been updated to creative."
System Chat Message (overlay)	Template:Tc	Template:Tc	Template:Tc	Game state information that is displayed above the hot bar, such as "You may not rest now, the bed is too far away".

Here's a matrix comparing what the client may send based on its chat setting:

Serverbound packet	Client setting
	Full	Commands only	Hidden
Chat Message	Template:Tc	Template:Tc	Template:Tc
Chat Command	Template:Tc	Template:Tc	Template:Tc

If the client attempts to send a chat message and the server rejects it, the Notchian server will send that client a System Chat Message (non-overlay) with a red chat.disabled.options translation component (which becomes "Chat disabled in client options.").

Social Interactions (blocking)

1.16 added a social interactions screen that lets players block chat from other players. Blocking takes place clientside by detecting whether a message is from a blocked player.

Player Chat Message packets are blocked based on the included sender UUID.

Disguised Chat Message packets are never blocked.

System Chat Message packets (regardless of the Overlay field!) are blocked based on the first occurrence of <playername> anywhere in the message, including split across multiple text components, where playername may be any text, including the empty string or whitespace. If playername is the name of a blocked player (matched case-sensitively), the message is blocked. This only occurs if Hide Matched Names is enabled in Chat Settings (the default).

Notes

<references group="note" /> Template:License wiki.vg