You can add a chat room to your page so that participants can communicate with each other.

Basic usage

Wherever you want a chatbox in your template, use:

{% chat %}

This will make a chat room among players in the same Group, where each player’s nickname is displayed as “Player 1”, “Player 2”, etc. (based on the player’s id_in_group).

Customizing the nickname and chat room members

You can pass optional parameters channel and/or nickname like this:

{% chat nickname="abc" channel="123" %}


nickname is the nickname that will be displayed for that user in the chat. A typical usage would be {% chat nickname=player.role %}.


channel is the chat room’s name, meaning that if 2 players have the same channel, they can chat with each other. channel is not displayed in the user interface; it’s just used internally. Its default value is, meaning all players in the group can chat together. You can use channel to instead scope the chat to the current page or sub-division of a group, etc. (see examples below). Regardless of the value of the channel argument, the chat will at least be scoped to players in the same session and the same app.

Example: chat by role

Here’s an example where instead of communication within a group, we have communication between groups based on role, e.g. all buyers can talk with each other, and all sellers can talk with each other.

class Player(BasePlayer):

    def role(self):
        if self.id_in_group == 1:
            return 'Seller'
            return 'Buyer'

    def chat_nickname(self):
        return 'Group {} {}'.format(, self.role())

Then in the template:

{% chat nickname=player.chat_nickname channel=player.role %}

Example: chat across rounds

If you need players to chat with players who are currently in a different round of the game, you can do:

{% chat channel=group.id_in_subsession %}

Example: chat between all groups in all rounds

If you want everyone in the session to freely chat with each other, just do:

{% chat channel=1 %}

(The number 1 is not significant; all that matters is that it’s the same for everyone.)

Advanced customization

If you look at the chat widget in your browser’s inspector, you will see the following selectors are available:

Element CSS/jQuery selector
Entire chat widget .otree-chat
Textbox to type a message .otree-chat__input (note: __, not _)
Button to submit a message .otree-chat__btn-send
Div with all messages .otree-chat__messages
Message .otree-chat__msg
Message’s nickname .otree-chat__nickname
Message’s body text .otree-chat__body

You can use CSS or JS to change the appearance or behavior of these elements (or hide them entirely).

For example, to customize the style, just include some CSS after the {% chat %} element, e.g.:

{% chat %}

    .otree-chat__messages {
        height: 400px;
    .otree-chat__nickname {
        color: #0000FF;
        font-weight: bold;

Note that there are 2 underscores (__, not _).

You can also customize the appearance by putting it inside a <div> and styling that parent <div>. For example, to set the width:

<div style="width: 400px">
    {% chat %}

Multiple chats on a page

You can have multiple {% chat %} boxes on each page, so that a player can be in multiple channels simultaneously.

For example, this code enables 1:1 chat with every other player in the group.

class Player(BasePlayer):

    def chat_nickname(self):
        return 'Player {}'.format(self.id_in_group)

    def chat_configs(self):
        configs = []
        for other in self.get_others_in_group():
            if other.id_in_group < self.id_in_group:
                lower_id, higher_id = other.id_in_group, self.id_in_group
                lower_id, higher_id = self.id_in_group, other.id_in_group
                # make a name for the channel that is the same for all
                # channel members. That's why we order it (lower, higher)
                'channel': '{}-{}-{}'.format(, lower_id, higher_id),
                'label': 'Chat with {}'.format(other.chat_nickname())
        return configs
{% for config in player.chat_configs %}
    <h4>{{ config.label }}</h4>
    {% chat nickname=player.chat_nickname %}
{% endfor %}

Exporting CSV of chat logs

The chat logs download link will appear on oTree’s regular data export page.