Skip to content
Block Kit for React
Esc
↑↓navigate↵open⌘Jpreview
On this page

Section

A text block that can pair with fields or a single accessory element, and the block you'll reach for most often.

A section is the most flexible block in Block Kit. It shows a block of text, or up to 10 short fields laid out in two columns, and can add one interactive or decorative element alongside as an accessory.

Your AppAPP
This is a section block with a button.

Fields

PropType
typestring

Always `"section"`.

Typestring
text?text object

The text to show, as a `plain_text` or `mrkdwn` text object. Required unless `fields` is set. 1–3000 characters.

Typetext object
fields?text object[]

Text objects rendered as two side-by-side columns. Required if `text` is omitted. Slack allows up to 10 fields, each up to 2000 characters.

Typetext object[]
accessory?element

One element shown alongside the text: a button, select, checkboxes, radio buttons, date/time picker, overflow menu, or image.

Typeelement
expand?boolean

When `true`, long text always renders in full. When `false` or omitted, text past a few lines collapses behind a "Show more" toggle.

Typeboolean
Defaultfalse
block_id?string

A unique identifier for the block, up to 255 characters. Slack generates one if omitted.

Typestring

Examples

Plain text

Your AppAPP
This is a plain text section block.

Markdown text

mrkdwn text supports bold, strikethrough, links, and emoji shortcodes.

Your AppAPP
This is a mrkdwn section block :ghost: this is bold, and this is crossed out, and this is a link

Fields

Fields render as two columns. Combine text and fields on the same section to pair a summary line with structured details.

Your AppAPP
Order #1042 is ready for review.
Customer
Ada Lovelace
Total
$1,234.00
Plain field :tada:

Accessories

Buttons, selects, and other elements sit to the right of the text. checkboxes and radio_buttons are the exception: Slack stacks those full-width below the text instead.

Your AppAPP
Pick an item from the dropdown list
Your AppAPP
This is a section block with an overflow menu.
Your AppAPP
This is a section block with checkboxes.
Your AppAPP
Pick a date for the deadline.
Your AppAPP
Farmhouse Thai Cuisine
:star::star::star::star: 1528 reviews
alt text for image

Long text with expand

Text past roughly 300 characters collapses behind a “Show more” toggle unless expand is set to true.

Your AppAPP
This is a long line of mrkdwn text meant to demonstrate the automatic text clamping behavior when the text is really long, sometimes people wanna post a lot of text and that's when this really shows its value, so with this change, the text will be clamped after five lines of text, and will present a show more button to expand the text block.

Set expand: true on the same block and the full text renders with no toggle.

Interactivity

Every accessory that can act reports through onAction with the block’s block_id, the element’s action_id, and a payload shaped for that element type.

Your AppAPP
Assign this to a teammate.
onActionInteract with the preview.

A users_select selection dispatches:

{
  "type": "users_select",
  "block_id": "…",
  "action_id": "assignee-select",
  "selected_user": "U0ADA",
  "action_ts": "…"
}

Buttons include value (and url/style when set); other selects include selected_option, selected_options, selected_date, or selected_conversation in place of selected_user, matching the field Slack documents for that element.

Header

A bold, single-line title block.

Actions

A row of interactive elements on their own.

Context

Small, muted supplementary text or images.

Input

Collect input inside a modal or workflow step.

Was this page helpful?