The Slack developer docs are moving! We've been working hard at building out a new docs experience at docs.slack.dev — now in beta! You can start using the new docs today, but we'll keep the content on both sites up to date during the transition.

Reference: Block Kit

Block Kit is made up of many atomic building blocks.

Blocks are visual components that can be arranged to create app layouts. Apps can add blocks to surfaces like App Home, messages and modals.

Blocks may also contain block elements. Block elements are usually interactive components, such as buttons and menus.

Blocks and block elements are built with composition objects. Composition objects define text, options, or other interactive features within certain blocks and block elements.

Block	Description
Actions block	Holds multiple interactive elements.
Context block	Provides contextual info, which can include both images and text.
Divider block	Visually separates pieces of info inside of a message.
File block	Displays info about remote files.
Header block	Displays a larger-sized text block.
Image block	Displays an image.
Input block	Collects information from users via block elements.
Rich text block	Displays formated, structured representation of text.
Section block	Displays text, possibly alongside block elements.
Video block	Displays an embedded video player.

Block element	Description
Button element	Allows users a direct path to performing basic actions.
Checkboxes element	Allows users to choose multiple items from a list of options.
Date picker element	Allows users to select a date from a calendar style UI.
Datetime picker element	Allows users to select both a date and a time of day.
Email input element	Allows user to enter an email into a single-line field.
Image element	Displays an image as part of a larger block of content.
Multi-select menu element	Allows users to select multiple items from a list of options.
Number input element	Allows user to enter a number into a single-line field.
Overflow menu element	Allows users to press a button to view a list of options.
Plain-text input element	Allows users to enter freeform text data into a single-line or multi-line field.
Radio buttons element	Allows users to choose one item from a list of possible options.
Rich text input element	Allows users to enter formatted text in a WYSIWYG composer, offering the same messaging writing experience as in Slack.
Select menu element	Allows users to choose an option from a drop down menu.
Time picker element	Allows users to enter numerical data into a single-line field.
URL input element	Allows user to enter a URL into a single-line field.
Workflow button element	Allows users to run a link trigger with customizable inputs.

Composition object	Description
Confirmation dialog object	Provides a dialog that adds a confirmation step to interactive elements.
Conversations filter object	Provides a way to filter the list of options in conversation selector menus.
Dispatch action configuration object	Defines when a plain-text input element will return a `block_actions` interaction payload.
Input parameter object	Defines an object containing information about an input parameter.
Option object	Represents a single item in a number of item selection elements.
Option group object	Used to group option objects in select menus.
Text object	Defines text for many different blocks and elements.
Trigger object	Defines an object containing trigger information.
Workflow object	Defines an object containing workflow information.
Slack file object	Defines an object containing Slack file information to be used in an image block or image element.