Actions are the things your bot runs in response to user input. There are four kinds of actions in Rasa:

  1. Utterance actions: start with utter_ and send a specific message to the user.

  2. Retrieval actions: start with respond_ and send a message selected by a retrieval model.

  3. Custom actions: run arbitrary code and send any number of messages (or none).

  4. Default actions: e.g. action_listen, action_restart, action_default_fallback.

Utterance Actions

To define an utterance action (ActionUtterTemplate), add a response to the domain file that starts with utter_:

    - "this is what I want my action to say!"

It is conventional to start the name of an utterance action with utter_. If this prefix is missing, you can still use the response in your custom actions, but the response can not be directly predicted as its own action. See Responses for more details.

If you use an external NLG service, you don’t need to specify the responses in the domain, but you still need to add the utterance names to the actions list of the domain.

Retrieval Actions

Retrieval actions make it easier to work with a large number of similar intents like chitchat and FAQs. See Retrieval Actions to learn more.

Custom Actions

An action can run any code you want. Custom actions can turn on the lights, add an event to a calendar, check a user’s bank balance, or anything else you can imagine.

Rasa will call an endpoint you can specify, when a custom action is predicted. This endpoint should be a webserver that reacts to this call, runs the code and optionally returns information to modify the dialogue state.

To specify, your action server use the endpoints.yml:

  url: "http://localhost:5055/webhook"

And pass it to the scripts using --endpoints endpoints.yml.

You can create an action server in node.js, .NET, java, or any other language and define your actions there - but we provide a small python SDK to make development there even easier.


Rasa uses a ticket lock mechanism to ensure incoming messages from the same conversation ID do not interfere with each other and are processed in the right order. If you expect your custom action to take more than 60 seconds to run, please set the TICKET_LOCK_LIFETIME environment variable to your expected value.

Custom Actions Written in Python

For actions written in python, we have a convenient Rasa SDK which starts this action server for you.

Execute Actions in Other Code

Rasa will send an HTTP POST request to your server containing information on which action to run. Furthermore, this request will contain all information about the conversation. Action Server shows the detailed API spec.

As a response to the action call from Rasa, you can modify the tracker, e.g. by setting slots and send responses back to the user. All of the modifications are done using events. There is a list of all possible event types in Events.

Default Actions

The available default actions are:


Stop predicting more actions and wait for user input.


Reset the whole conversation. Can be triggered during a conversation by entering /restart if the Mapping Policy is included in the policy configuration.


Start a new conversation session. Take all set slots, mark the beginning of a new conversation session and re-apply the existing SlotSet events. This action is triggered automatically after an inactivity period defined by the session_expiration_time parameter in the domain’s Session configuration. Can be triggered manually during a conversation by entering /session_start. All conversations begin with an action_session_start.


Undo the last user message (as if the user did not send it and the bot did not react) and utter a message that the bot did not understand. See Fallback Actions.


Deactivate the active form and reset the requested slot. See also Handling unhappy paths.


Revert events that occurred during the TwoStageFallbackPolicy. See Fallback Actions.


Ask the user to affirm their intent. It is suggested to overwrite this default action with a custom action to have more meaningful prompts.


Ask the user to rephrase their intent.


Undo the last user message (as if the user did not send it and the bot did not react). Can be triggered during a conversation by entering /back if the MappingPolicy is included in the policy configuration.

All the default actions can be overridden. To do so, add the action name to the list of actions in your domain:

- action_default_ask_affirmation

Rasa will then call your action endpoint and treat it as every other custom action.