Reference: block elements & interactive components

Button element

Allows users a direct path to performing basic actions.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always button.	Yes
text	Object	A text object that defines the button's text. Can only be of type: plain_text. text may truncate with ~30 characters. Maximum length for the text in this field is 75 characters.	Yes
action_id	String	An identifier for this action. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
url	String	A URL to load in the user's browser when the button is clicked. Maximum length is 3000 characters. If you're using url, you'll still receive an interaction payload and will need to send an acknowledgement response.	No
value	String	The value to send along with the interaction payload. Maximum length is 2000 characters.	No
style	String	Decorates buttons with alternative visual color schemes. Use this option with restraint. primary gives buttons a green outline and text, ideal for affirmation or confirmation actions. primary should only be used for one button within a set. danger gives buttons a red outline and text, and should be used when the action is destructive. Use danger even more sparingly than primary. If you don't include this field, the default button style will be used.	No
confirm	Object	A confirm object that defines an optional confirmation dialog after the button is clicked.	No
accessibility_label	String	A label for longer descriptive text about a button element. This label will be read out by screen readers instead of the button text object. Maximum length is 75 characters.	No

Examples

A regular interactive button:

{
  "type": "button",
  "text": {
    "type": "plain_text",
    "text": "Click Me"
  },
  "value": "click_me_123",
  "action_id": "button"
}

A button with a primary style attribute:

{
  "type": "button",
  "text": {
    "type": "plain_text",
    "text": "Save"
  },
  "style": "primary",
  "value": "click_me_123",
  "action_id": "button"
}

A link button:

{
  "type": "button",
  "text": {
    "type": "plain_text",
    "text": "Link Button"
  },
  "url": "https://api.slack.com/block-kit"
}

View an example in Block Kit builder

Checkboxes element

Allows users to choose multiple items from a list of options.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always checkboxes.	Yes
action_id	String	An identifier for the action triggered when the checkbox group is changed. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
options	Object[]	An array of option objects. A maximum of 10 options are allowed.	Yes
initial_options	Object[]	An array of option objects that exactly matches one or more of the options within options. These options will be selected when the checkbox group initially loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after clicking one of the checkboxes in this element.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No

Example

A section block containing a group of checkboxes:

{
	"type": "modal",
	"title": {
		"type": "plain_text",
		"text": "My App",
		"emoji": true
	},
	"submit": {
		"type": "plain_text",
		"text": "Submit",
		"emoji": true
	},
	"close": {
		"type": "plain_text",
		"text": "Cancel",
		"emoji": true
	},
	"blocks": [
		{
			"type": "section",
			"text": {
				"type": "plain_text",
				"text": "Check out these charming checkboxes"
			},
			"accessory": {
				"type": "checkboxes",
				"action_id": "this_is_an_action_id",
				"initial_options": [{
					"value": "A1",
					"text": {
						"type": "plain_text",
						"text": "Checkbox 1"
					}
				}],
				"options": [
					{
						"value": "A1",
						"text": {
							"type": "plain_text",
							"text": "Checkbox 1"
						}
					},
					{
						"value": "A2",
						"text": {
							"type": "plain_text",
							"text": "Checkbox 2"
						}
					}
				]
			}
		}
	]
}

View an example in Block Kit builder

Date picker element

Allows users to select a date from a calendar style UI.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always datepicker.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_date	String	The initial date that is selected when the element is loaded. This should be in the format YYYY-MM-DD.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a date is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the datepicker. Maximum length for the text in this field is 150 characters.	No

Example

A section block containing a datepicker element:

{
  "type": "section",
  "block_id": "section1234",
  "text": {
    "type": "mrkdwn",
    "text": "Pick a date for the deadline."
  },
  "accessory": {
    "type": "datepicker",
    "action_id": "datepicker123",
    "initial_date": "1990-04-28",
    "placeholder": {
      "type": "plain_text",
      "text": "Select a date"
    }
  }
}

View an example in Block Kit builder

Datetime picker element

Allows users to select both a date and a time of day, formatted as a Unix timestamp.

Interactive component - see our guide to enabling interactivity.

On desktop clients, the time picker will take the form of a dropdown list and the date picker will take the form of a dropdown calendar. Both options will have free-text entry for precise choices. On mobile clients, the time picker and date picker will use native UIs.

Available in surfaces	Works with block types
Modals Messages	Actions Input

Example:

Fields

Fields	Type	Description	Required?
type	String	The type of element. In this case type is always datetimepicker.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_date_time	Integer	The initial date and time that is selected when the element is loaded, represented as a UNIX timestamp in seconds. This should be in the format of 10 digits, for example 1628633820 represents the date and time August 10th, 2021 at 03:17pm PST.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a time is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No

Example

An input block containing a datetime picker element:

{
  "type": "input",
  "element": {
    "type": "datetimepicker",
    "action_id": "datetimepicker-action"
  },
  "hint": {
    "type": "plain_text",
    "text": "This is some hint text",
    "emoji": true
  },
  "label": {
    "type": "plain_text",
    "text": "Start date",
    "emoji": true
  }
}

Email input element

Allows user to enter an email into a single-line field.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals	Input

Fields

Fields	Type	Description	Required?
type	String	The type of element. In this case type is always email_text_input.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_value	String	The initial value in the email input when it is loaded.	No
dispatch_action_config	Object	A dispatch configuration object that determines when during text input the element returns a block_actions payload.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown in the email input. Maximum length for the text in this field is 150 characters.	No

Example

An input block containing a email-text input element.

{
  "type": "input",
  "block_id": "input123",
  "label": {
    "type": "plain_text",
    "text": "Email Address"
  },
  "element": {
    "type": "email_text_input",
    "action_id": "email_text_input-action",
    "placeholder": {
      "type": "plain_text",
      "text": "Enter an email"
    }
  }
}

File input element

Allows user to upload files.

In order to use the file_input element within your app, your app must have the files:read scope.

Available in surfaces	Works with block types
Modals	Input

Fields

Fields	Type	Description	Required?
type	String	The type of element. In this case type is always file_input.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
filetypes	String[]	An array of valid file extensions that will be accepted for this element. All file extensions will be accepted if filetypes is not specified. This validation is provided for convenience only, and you should perform your own file type validation based on what you expect to receive.	No
max_files	Integer	Maximum number of files that can be uploaded for this file_input element. Minimum of 1, maximum of 10. Defaults to 10 if not specified.	No

Example

An input block containing a file_input input element.

{
  "type": "input",
  "block_id": "input_block_id",
  "label": {
    "type": "plain_text",
    "text": "Upload Files"
  },
  "element": {
    "type": "file_input",
    "action_id": "file_input_action_id_1",
    "filetypes": ["jpg", "png"],
    "max_files": 5,
  },
}

Image element

Displays an image as part of a larger block of content.

Use the image block if you want a block with only an image in it.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Context

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always image.	Yes
image_url	String	The URL of the image to be displayed.	Yes
alt_text	String	A plain-text summary of the image. This should not contain any markup.	Yes

Example

{
  "type": "image",
  "image_url": "http://placekitten.com/700/500",
  "alt_text": "Multiple cute kittens"
}

View an example in Block Kit builder

Multi-select menu element

Allows users to select multiple items from a list of options.

Interactive component - see our guide to enabling interactivity.

Just like regular select menus, multi-select menus also include type-ahead functionality, where a user can type a part or all of an option string to filter the list.

There are different types of multi-select menu that depend on different data sources for their lists of options:

• Menu with static options
• Menu with external data source
• Menu with user list
• Menu with conversations list
• Menu with channels list

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

Example:

---

Static options

This is the most basic form of select menu, with a static list of options passed in when defining the element.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always multi_static_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
options	Object[]	An array of option objects. Maximum number of options is 100. Each option must be less than 76 characters. If option_groups is specified, this field should not be.	Yes
option_groups	Object[]	An array of option group objects. Maximum number of option groups is 100. If options is specified, this field should not be.	No
initial_options	Object[]	An array of option objects that exactly match one or more of the options within options or option_groups. These options will be selected when the menu initially loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears before the multi-select choices are submitted.	No
max_selected_items	Integer	Specifies the maximum number of items that can be selected in the menu. Minimum number is 1.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A static multi-select menu

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick items from the list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "multi_static_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select items"
      },
      "options": [
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-0"
        },
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-1"
        },
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-2"
        }
      ]
    }
  }
]

View an example in Block Kit builder

---

External data source

This menu will load its options from an external data source, allowing for a dynamic list of options.

Setup

To use this menu type, you'll need to configure your app first:

1. Go to your app's settings page and select Interactivity & Shortcuts from the sidebar.
2. Add a URL to the Options Load URL under Select Menus.
3. Save changes.

Each time a menu of this type is opened or the user starts typing in the typeahead field, we'll send a request to your specified URL. Your app should return an HTTP 200 OK response, along with an application/json post body with an object containing either:

• an options array
• an option_groups array

The option_groups array can have a maximum number of 100 option groups with a maximum of 100 options.

Here's an example response:

{
  "options": [
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-0"
    },
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-1"
    },
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-2"
    }
  ]
}

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always multi_external_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
min_query_length	Integer	When the typeahead field is used, a request will be sent on every character change. If you prefer fewer requests or more fully ideated queries, use the min_query_length attribute to tell Slack the fewest number of typed characters required before dispatch. The default value is 3.	No
initial_options	Object[]	An array of option objects that exactly match one or more of the options within options or option_groups. These options will be selected when the menu initially loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears before the multi-select choices are submitted.	No
max_selected_items	Integer	Specifies the maximum number of items that can be selected in the menu. Minimum number is 1.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A multi-select menu in a section block with an external data source:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick items from the list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "multi_external_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select items"
      },
      "min_query_length": 3
    }
  }
]

---

User list

This multi-select menu will populate its options with a list of Slack users visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always multi_users_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_users	String[]	An array of user IDs of any valid users to be pre-selected when the menu loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears before the multi-select choices are submitted.	No
max_selected_items	Integer	Specifies the maximum number of items that can be selected in the menu. Minimum number is 1.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A multi-select menu in a section block showing a list of users:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick users from the list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "multi_users_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select users"
      }
    }
  }
]

---

Conversations list

This multi-select menu will populate its options with a list of public and private channels, DMs, and MPIMs visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always multi_conversations_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_conversations	String[]	An array of one or more IDs of any valid conversations to be pre-selected when the menu loads. If default_to_current_conversation is also supplied, initial_conversations will be ignored.	No
default_to_current_conversation	Boolean	Pre-populates the select menu with the conversation that the user was viewing when they opened the modal, if available. Default is false.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears before the multi-select choices are submitted.	No
max_selected_items	Integer	Specifies the maximum number of items that can be selected in the menu. Minimum number is 1.	No
filter	Object	A filter object that reduces the list of available conversations using the specified criteria.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A multi-select menu in a section block showing a list of conversations:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick conversations from the list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "multi_conversations_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select conversations"
      }
    }
  }
]

---

Public channels select

This multi-select menu will populate its options with a list of public channels visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always multi_channels_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_channels	String[]	An array of one or more IDs of any valid public channel to be pre-selected when the menu loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears before the multi-select choices are submitted.	No
max_selected_items	Integer	Specifies the maximum number of items that can be selected in the menu. Minimum number is 1.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A multi-select menu in a section block showing a list of channels:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick channels from the list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "multi_channels_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select channels"
      }
    }
  }
]

Number input element

Allows user to enter a number into a single-line field.

Interactive component - see our guide to enabling interactivity.

The number input element accepts both whole and decimal numbers. For example, 0.25, 5.5, and -10 are all valid input values. Decimal numbers are only allowed when is_decimal_allowed is equal to true.

Available in surfaces	Works with block types
Modals	Input

Example:

Fields

Fields	Type	Description	Required?
type	String	The type of element. In this case type is always number_input.	Yes
is_decimal_allowed	Boolean	Decimal numbers are allowed if is_decimal_allowed= true, set the value to false otherwise.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_value	String	The initial value in the plain-text input when it is loaded.	No
min_value	String	The minimum value, cannot be greater than max_value.	No
max_value	String	The maximum value, cannot be less than min_value.	No
dispatch_action_config	Object	A dispatch configuration object that determines when during text input the element returns a block_actions payload.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown in the number input. Maximum length for the text in this field is 150 characters.	No

Example

{
"type": "input",
  "element": {
    "type": "number_input",
    "is_decimal_allowed": false,
    "action_id": "number_input-action"
  },
  "label": {
    "type": "plain_text",
    "text": "Label",
    "emoji": true
  }
}

Overflow menu element

Allows users to press a button to view a list of options.

Interactive component - see our guide to enabling interactivity.

Unlike the select menu, there is no typeahead field, and the button always appears with an ellipsis ("…") rather than customizable text. As such, it is usually used if you want a more compact layout than a select menu, or to supply a list of less visually important actions after a row of buttons. You can also specify URL links as overflow menu options, instead of actions.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always overflow.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
options	Object[]	An array of up to five option objects to display in the menu.	Yes
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No

Example

A section block with an overflow menu:

{
  "type": "section",
  "block_id": "section 890",
  "text": {
    "type": "mrkdwn",
    "text": "This is a section block with an overflow menu."
  },
  "accessory": {
    "type": "overflow",
    "options": [
      {
        "text": {
          "type": "plain_text",
          "text": "*this is plain_text text*"
        },
        "value": "value-0"
      },
      {
        "text": {
          "type": "plain_text",
          "text": "*this is plain_text text*"
        },
        "value": "value-1"
      },
      {
        "text": {
          "type": "plain_text",
          "text": "*this is plain_text text*"
        },
        "value": "value-2"
      },
      {
        "text": {
          "type": "plain_text",
          "text": "*this is plain_text text*"
        },
        "value": "value-3"
      },
      {
        "text": {
          "type": "plain_text",
          "text": "*this is plain_text text*"
        },
        "value": "value-4"
      }
    ],
    "action_id": "overflow"
  }
}

View an example in Block Kit builder

Plain-text input element

Allows users to enter freeform text data into a single-line or multi-line field.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Messages Home tabs	Input

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always plain_text_input.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_value	String	The initial value in the plain-text input when it is loaded.	No
multiline	Boolean	Indicates whether the input will be a single line (false) or a larger textarea (true). Defaults to false.	No
min_length	Integer	The minimum length of input that the user must provide. If the user provides less, they will receive an error. Acceptable values for this field are between 0 and 3000, inclusive.	No
max_length	Integer	The maximum length of input that the user can provide. If the user provides more, they will receive an error. Acceptable values for this field are between 1 and 3000, inclusive.	No
dispatch_action_config	Object	A dispatch configuration object that determines when during text input the element returns a block_actions payload.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown in the plain-text input. Maximum length for the text in this field is 150 characters.	No

Example

An input block containing a plain-text input element.

{
  "type": "input",
  "block_id": "input123",
  "label": {
    "type": "plain_text",
    "text": "Label of input"
  },
  "element": {
    "type": "plain_text_input",
    "action_id": "plain_input",
    "placeholder": {
      "type": "plain_text",
      "text": "Enter some plain text"
    }
  }
}

View an example in Block Kit builder

Radio button group element

Allows users to choose one item from a list of possible options.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always radio_buttons.	Yes
action_id	String	An identifier for the action triggered when the radio button group is changed. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
options	Object[]	An array of option objects. A maximum of 10 options are allowed.	Yes
initial_option	Object	An option object that exactly matches one of the options within options. This option will be selected when the radio button group initially loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after clicking one of the radio buttons in this element.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No

Example

A section block containing a set of radio buttons:

{
  "type": "modal",
  "title": {
    "type": "plain_text",
    "text": "My App",
    "emoji": true
  },
  "submit": {
    "type": "plain_text",
    "text": "Submit",
    "emoji": true
  },
  "close": {
    "type": "plain_text",
    "text": "Cancel",
    "emoji": true
  },
  "blocks": [
    {
      "type": "section",
      "text": {
        "type": "plain_text",
        "text": "Check out these rad radio buttons"
      },
      "accessory": {
        "type": "radio_buttons",
        "action_id": "this_is_an_action_id",
        "initial_option": {
          "value": "A1",
          "text": {
            "type": "plain_text",
            "text": "Radio 1"
          }
        },
        "options": [
          {
            "value": "A1",
            "text": {
              "type": "plain_text",
              "text": "Radio 1"
            }
          },
          {
            "value": "A2",
            "text": {
              "type": "plain_text",
              "text": "Radio 2"
            }
          }
        ]
      }
    }
  ]
}

View an example in Block Kit builder

Rich text input element

Allows users to enter formatted text in a WYSIWYG composer, offering the same messaging writing experience as in Slack.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals Home tabs	Input

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always rich_text_input.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique in the containing block. Maximum length is 255 characters.	Yes
initial_value	Rich text	The initial value in the rich text input when it is loaded.	No
dispatch_action_config	Object	A dispatch configuration object that determines when during text input the element returns a block_actions payload.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text object that defines the placeholder text shown in the plain-text input. Maximum length for the text in this field is 150 characters.	No

Example

An input block containing a rich text input element.

{
  "type": "rich_text_input",
  "action_id": "rich_text_input-action",
  "dispatch_action_config": {
    "trigger_actions_on": [
      "on_character_entered"
    ]
  },
  "focus_on_load": true,
  "placeholder": {
    "type": "plain_text",
    "text": "Enter text"
  }
}

Select menu element

Allows users to choose an option from a drop down menu.

Interactive component - see our guide to enabling interactivity.

The select menu also includes type-ahead functionality, where a user can type a part or all of an option string to filter the list.

There are different types of select menu elements that depend on different data sources for their lists of options:

• Select menu of static options
• Select menu of external data source
• Select menu of users
• Select menu of conversations
• Select menu of public channels

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

---

Select menu of static options

This is the most basic form of select menu, with a static list of options passed in when defining the element.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always static_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
options	Object[]	An array of option objects. Maximum number of options is 100. If option_groups is specified, this field should not be.	Yes
option_groups	Object[]	An array of option group objects. Maximum number of option groups is 100. If options is specified, this field should not be.	No
initial_option	Object	A single option that exactly matches one of the options within options or option_groups. This option will be selected when the menu initially loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A static select menu

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick an item from the dropdown list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "static_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select an item"
      },
      "options": [
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-0"
        },
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-1"
        },
        {
          "text": {
            "type": "plain_text",
            "text": "*this is plain_text text*"
          },
          "value": "value-2"
        }
      ]
    }
  }
]

---

Select menu of external data source

This select menu will load its options from an external data source, allowing for a dynamic list of options.

Setup

If you don't have Socket Mode enabled, you'll need to configure your app to use this menu type:

1. Go to your app's settings page and select Interactivity & Shortcuts from the sidebar.
2. Add a URL to the Options Load URL under Select Menus.
3. Save changes.

Each time a select menu of this type is opened or the user starts typing in the typeahead field, we'll send a request to your specified URL. Your app should return an HTTP 200 OK response, along with an application/json post body with an object containing either:

• an options array
• an option_groups array

The option_groups array can have a maximum number of 100 option groups with a maximum of 100 options.

Here's an example response:

{
  "options": [
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-0"
    },
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-1"
    },
    {
      "text": {
        "type": "plain_text",
        "text": "*this is plain_text text*"
      },
      "value": "value-2"
    }
  ]
}

Refer to options and option_groups for more information about their related fields.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always external_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_option	Object	A single option that exactly matches one of the options within the options or option_groups loaded from the external data source. This option will be selected when the menu initially loads.	No
min_query_length	Integer	When the typeahead field is used, a request will be sent on every character change. If you prefer fewer requests or more fully ideated queries, use the min_query_length attribute to tell Slack the fewest number of typed characters required before dispatch. The default value is 3.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A select menu in a section block with an external data source:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick an item from the dropdown list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "external_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select an item"
      },
      "min_query_length": 3
    }
  }
]

---

Select menu of users

This select menu will populate its options with a list of Slack users visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always users_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_user	String	The user ID of any valid user to be pre-selected when the menu loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A select menu in a section block showing a list of users:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick a user from the dropdown list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "users_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select an item"
      }
    }
  }
]

---

Select menu of conversations

This select menu will populate its options with a list of public and private channels, DMs, and MPIMs visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always conversations_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_conversation	String	The ID of any valid conversation to be pre-selected when the menu loads. If default_to_current_conversation is also supplied, initial_conversation will take precedence.	No
default_to_current_conversation	Boolean	Pre-populates the select menu with the conversation that the user was viewing when they opened the modal, if available. Default is false.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No
response_url_enabled	Boolean	This field only works with menus in input blocks in modals. When set to true, the view_submission payload from the menu's parent view will contain a response_url. This response_url can be used for message responses. The target conversation for the message will be determined by the value of this select menu.	No
filter	Object	A filter object that reduces the list of available conversations using the specified criteria.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A select menu in a section block showing a list of conversations:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick a conversation from the dropdown list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "conversations_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select an item"
      }
    }
  }
]

---

Select menu of public channels

This select menu will populate its options with a list of public channels visible to the current user in the active workspace.

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always channels_select.	Yes
action_id	String	An identifier for the action triggered when a menu option is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_channel	String	The ID of any valid public channel to be pre-selected when the menu loads.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a menu item is selected.	No
response_url_enabled	Boolean	This field only works with menus in input blocks in modals. When set to true, the view_submission payload from the menu's parent view will contain a response_url. This response_url can be used for message responses. The target channel for the message will be determined by the value of this select menu.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the menu. Maximum length for the text in this field is 150 characters.	No

Example

A select menu in a section block showing a list of channels:

[
  {
    "type": "section",
    "block_id": "section678",
    "text": {
      "type": "mrkdwn",
      "text": "Pick a channel from the dropdown list"
    },
    "accessory": {
      "action_id": "text1234",
      "type": "channels_select",
      "placeholder": {
        "type": "plain_text",
        "text": "Select an item"
      }
    }
  }
]

Time picker element

Allows users to select a time of day.

Interactive component - see our guide to enabling interactivity.

On desktop clients, this time picker will take the form of a dropdown list with free-text entry for precise choices. On mobile clients, the time picker will use native time picker UIs.

Available in surfaces	Works with block types
Modals Messages Home tabs	Section Actions Input

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always timepicker.	Yes
action_id	String	An identifier for the action triggered when a time is selected. You can use this when you receive an interaction payload to identify the source of the action. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_time	String	The initial time that is selected when the element is loaded. This should be in the format HH:mm, where HH is the 24-hour format of an hour (00 to 23) and mm is minutes with leading zeros (00 to 59), for example 22:25 for 10:25pm.	No
confirm	Object	A confirm object that defines an optional confirmation dialog that appears after a time is selected.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown on the time picker. Maximum length for the text in this field is 150 characters.	No
timezone	String	A string in the IANA format, e.g. "America/Chicago". The timezone is displayed to end users as hint text underneath the time picker. It is also passed to the app upon certain interactions, such as view_submission.	No

Example

A section block containing a time picker element, with the initial time set to 11:40am:

{
  "type": "section",
  "block_id": "section1234",
  "text": {
    "type": "mrkdwn",
    "text": "Pick a date for the deadline."
  },
  "accessory": {
    "type": "timepicker",
    "timezone": "America/Los_Angeles",
    "action_id": "timepicker123",
    "initial_time": "11:40",
    "placeholder": {
      "type": "plain_text",
      "text": "Select a time"
    }
  }
}

View an example in Block Kit builder

URL input element

Allows user to enter a URL into a single-line field.

Interactive component - see our guide to enabling interactivity.

Available in surfaces	Works with block types
Modals	Input

Fields

Fields	Type	Description	Required?
type	String	The type of element. In this case type is always url_text_input.	Yes
action_id	String	An identifier for the input value when the parent modal is submitted. You can use this when you receive a view_submission payload to identify the value of the input element. Should be unique among all other action_ids in the containing block. Maximum length is 255 characters.	No
initial_value	String	The initial value in the URL input when it is loaded.	No
dispatch_action_config	Object	A dispatch configuration object that determines when during text input the element returns a block_actions payload.	No
focus_on_load	Boolean	Indicates whether the element will be set to auto focus within the view object. Only one element can be set to true. Defaults to false.	No
placeholder	Object	A plain_text only text object that defines the placeholder text shown in the URL input. Maximum length for the text in this field is 150 characters.	No

Example

An input block containing a URL-text input element.

{
  "type": "input",
  "element": {
    "type": "url_text_input",
    "action_id": "url_text_input-action"
  },
  "label": {
    "type": "plain_text",
    "text": "Label",
    "emoji": true
  }
}

Workflow button element

Allows users to run a link trigger with customizable inputs

Interactive component - but interactions with workflow button elements will not send block_actions events, since these are used to start new workflow runs.

Available in surfaces	Works with block types
Messages	Section Actions

Example:

Fields

Field	Type	Description	Required?
type	String	The type of element. In this case type is always workflow_button.	Yes
text	Object	A text object that defines the button's text. Can only be of type: plain_text. text may truncate with ~30 characters. Maximum length for the text in this field is 75 characters.	Yes
workflow	Object	A workflow object that contains details about the workflow that will run when the button is clicked.	Yes
action_id	String	An identifier for the action. Use this when you receive an interaction payload to identify the source of the action. Every action_id in a block should be unique. Maximum length is 255 characters.	Yes
style	String	Decorates buttons with alternative visual color schemes. Use this option with restraint. primary gives buttons a green outline and text, ideal for affirmation or confirmation actions. primary should only be used for one button within a set. danger gives buttons a red outline and text, and should be used when the action is destructive. Use danger even more sparingly than primary. If you don't include this field, the default button style will be used.	No
accessibility_label	String	A label for longer descriptive text about a button element. This label will be read out by screen readers instead of the button text object. Maximum length is 75 characters.	No

Example

{
  "type": "workflow_button",
  "text": {
    "type": "plain_text",
    "text": "Run Workflow"
  },
  "action_id": "workflowbutton123",
  "workflow": {
    "trigger": {
        "url": "https://slack.com/shortcuts/Ft0123ABC456/xyz...zyx",
        "customizable_input_parameters": [
          {
            "name": "input_parameter_a",
            "value": "Value for input param A"
          },
          {
            "name": "input_parameter_b",
            "value": "Value for input param B"
          }
        ]
    }
  }
}