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

Basic usage

In your template HTML, put:

{{ 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 specify a 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 channel, 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.

def chat_nickname(player):
    group =

    return 'Group {} player {}'.format(group.id_in_subsession, player.id_in_group)

In the page:

class MyPage(Page):

    def vars_for_template(player):
        return dict(

Then in the template:

{{ chat nickname=nickname channel=player.id_in_group }}

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 page source code in your browser’s inspector, you will see a bunch of classes starting with otree-chat__.

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

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.

Exporting CSV of chat logs

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

See Chat between participants and experimenter.