Zulip bot system

Zulip’s features can be extended by the means of bots and integrations.

  • Integrations are used to connect Zulip with different chat, scheduling and workflow software. If this is what you are looking for, please check out the integrations guide.
  • Bots, as a more general concept, intercept and react to messages. If this is what you are looking for, read on!

The purpose of this documentation is to provide you with information about Zulip’s bot system.

On this page you’ll find:

  • A step-by-step tutorial on how to run a bot.
  • A step-by-step tutorial on how to develop a bot.
  • A documentation of the bot API.
  • Common problems when developing/running bots and their solutions.

Contributions to this guide are very welcome, so if you run into any issues following these instructions or come up with any tips or tools that help with writing bots, please visit #bots on the Zulip development community server, open an issue, or submit a pull request to share your ideas!

The bots system

Zulip’s bot system resides in the api directory.

The structure of the bots ecosystem in the api directory looks like the following:

        |   |
        |   └───lib1.py
├── bots_api
│   ├── bot_lib.py
│   ├── bots_test_lib.py
│   ├── run.py
│   ├── test_bots
├── integrations

Each subdirectory in bots contains a bot. When developing bots, try to use the structure outlined above as an orientation.

How to run a bot

This guide will show you how to run a bot on a running Zulip server. It assumes you want to use one of the existing api/bots bots in your Zulip organization. If you want to write a new one, you just need to write the <my-bot>.py script and put it into /api/bots/<my-bot> directory.

You need:

  • An account in an organization on a Zulip server (e.g. chat.zulip.org or yourSubdomain.zulipchat.com, or your own development server). Within that Zulip organization, users will be able to interact with your bot.
  • A computer where you’re running the bot from, with a clone of the Zulip repository, which contains the bot library code in its api/bots_api/<my-bot> subdirectory. This is required to run your bot. The following instructions assume this repository to be located in ~/zulip/.

Note: Please be considerate when testing experimental bots on public servers such as chat.zulip.org.

  1. Register a new bot user on the Zulip server’s web interface.

    • Log in to the Zulip server.
    • Navigate to Settings -> Your bots -> Add a new bot, fill out the form and click on Create bot.
    • A new bot user should appear in the Your bots panel.
  2. Download the bot’s zuliprc configuration file to your computer.

    • In the Your bots panel, click on the green icon to download its configuration file zuliprc (the structure of this file is explained here.)
    • Copy the file to a destination of your choice, e.g. to ~/.zuliprc or ~/zuliprc-test. Note that the destination should be accessible from your Zulip dev environment (e.g. Vagrant or Digital Ocean).
  3. Subscribe the bot to the streams that the bot needs to interact with.

    • To subscribe your bot to streams, navigate to Manage Streams. Select a stream and add your bot by its email address (the address you assigned in step 1).
    • Now, the bot can do its job on the streams you subscribed it to.
    • (In future versions of the API, this step may not be required).
  4. Run the bot.

    • In your Zulip repository, navigate to ~/zulip/api/bots_api/

    • Run

      python run.py ../bots/<my-bot>/<my-bot>.py --config-file ~/.zuliprc`

      (using the path to the .zuliprc file from step 2).

    • Check the output of the command. It should start with the text the usage function returns, followed by logging output similar to this:

      INFO:root:starting message handling...
      INFO:requests.packages.urllib3.connectionpool:Starting new HTTP connection (1): localhost
    • Congrats! Now, your bot should be ready to test on the streams you’ve subscribed it to.

Testing the helloworld bot

  • The helloworld bot is a simple bot that responds with a ‘beep boop’ when queried. It can be used as a template to build more complex bots.
  • Go to a stream your bot is subscribed to. Talk to the bot by typing @<your bot name> followed by some commands. If the bot is the helloworld bot, you should expect the bot to respond with “beep boop”.

How to develop a bot

The tutorial below explains the structure of a bot <my-bot>.py, which is the only file you need to create to develop a new bot. You can use this as boilerplate code for developing your own bot.

Every bot is built upon this structure:

class MyBotHandler(object):
    A docstring documenting this bot.

    def usage(self):
        return '''Your description of the bot'''

    def handle_message(self, message, client, state_handler):
        # add your code here

handler_class = MyBotHandler
  • The class name (in this case MyBotHandler) can be defined by you and should match the name of your bot. To register your bot’s class, adjust the last line handler_class = MyBotHandler to match your class name.
  • Every bot needs to implement the functions
    • usage(self)
    • handle_message(self, message, client)
  • These functions are documented in the next section.


This section documents functions available to the bot and the structure of the bot’s config file.

With this API, you can

  • intercept, view, and process messages sent by users on Zulip.
  • send out new messages as replies to the processed messages.

With this API, you cannot

  • modify an intercepted message (you have to send a new message).
  • send messages on behalf of or impersonate other users.
  • intercept private messages (except for PMs with the bot as an explicit recipient).



is called to retrieve information about the bot.


  • self - the instance the method is called on.

Return values

  • A string describing the bot’s functionality

Example implementation

def usage(self):
    return '''
        This plugin will allow users to flag messages
        as being follow-up items.  Users should preface
        messages with "@followup".
        Before running this, make sure to create a stream
        called "followup" that your API user can send to.


handle_message(self, message, client)

handles user message.


  • self - the instance the method is called on.
  • message - a dictionary describing a Zulip message
  • client - used to interact with the server, e.g. to send a message
  • state_handler - used to save states/information of the bot beta
    • use state_handler.set_state(state) to set a state (any object)
    • use state_handler.get_state() to retrieve the state set; returns a NoneType object if no state is set

Return values


Example implementation

 def handle_message(self, message, client, state_handler):
    original_content = message['content']
    original_sender = message['sender_email']
    new_content = original_content.replace('@followup',
                                           'from %s:' % (original_sender,))




will send a message as the bot user. Generally, this is less convenient than send_reply, but it offers additional flexibility about where the message is sent to.


  • message - a dictionary describing the message to be sent by the bot

Example implementation

    type='stream', # can be 'stream' or 'private'
    to=stream_name, # either the stream name or user's email
    subject=subject, # message subject
    content=message, # content of the sent message


client.send_reply(message, response)

will reply to the triggering message to the same place the original message was sent to, with the content of the reply being response.


  • message - Dictionary containing information on message to respond to (provided by handle_message).
  • response - Response message from the bot (string).



will edit the content of a previously sent message.


  • message - dictionary defining what message to edit and the new content


From /zulip/api/bots/incrementor/incrementor.py:

    message_id=self.message_id, # id of message to be updated
    content=str(self.number), # string with which to update message with

Configuration file

  • key - the API key you created for the bot; this is how Zulip knows the request is from an authorized user.
  • email - the email address of the bot, e.g. some-bot@zulip.com
  • site - your development environment URL; if you are working on a development environment hosted on your computer, use localhost:9991

Common problems

  • I modified my bot’s code, yet the changes don’t seem to have an effect.

    • Ensure that you restarted the run.py script.
  • My bot won’t start

    • Ensure that your API config file is correct (download the config file from the server).

    • Ensure that you bot script is located in zulip/api/bots/<my-bot>/

    • Are you using your own Zulip development server? Ensure that you run your bot outside the Vagrant environment.

    • Some bots require Python 3. Try switching to a Python 3 environment before running your bot:

      source /srv/zulip-py3-venv/bin/activate

      Note that you can switch back to a Python 2 environment as follows:

      source /srv/zulip-venv/bin/activate
  • My bot works only on some streams.

    • Subscribe your bot to other streams, as described here.

Future direction

The long-term plan for this bot system is to allow the same BotHandler code to eventually be usable in several contexts:

  • Run directly using the Zulip call_on_each_message API, which is how the implementation above works. This is great for quick development with minimal setup.
  • Run in a simple Python webserver server, processing messages received from Zulip’s outgoing webhooks integration.
  • For bots merged into the mainline Zulip codebase, enabled via a button in the Zulip web UI, with no code deployment effort required.