slack-mrkdwn
Slack mrkdwn
Slack's custom text formatting syntax for messages and text objects. Not standard Markdown.
CRITICAL: Two Markup Systems
Slack has two completely different markup syntaxes. Using the wrong one is the most common formatting mistake.
| System | Used In | Bold | Link | Heading |
|---|---|---|---|---|
| Slack mrkdwn | text field, text objects (type: "mrkdwn"), section fields |
*bold* |
<url|text> |
Not supported |
| Standard Markdown | markdown block only |
**bold** |
[text](url) |
# Heading |
Standard Markdown syntax (**bold**, [text](url), # Heading) renders as literal text in mrkdwn contexts. Slack mrkdwn syntax (*bold*, <url|text>) renders as literal text in markdown blocks. Never mix them.
The markdown block (type: "markdown") accepts standard Markdown and translates it for Slack rendering. Supports: headings, bold, italic, strikethrough, lists, links, blockquotes, code blocks with optional syntax highlighting, horizontal rules/dividers, tables, task lists, and images (rendered as link text). A single input block may produce multiple output blocks. Cumulative limit across all markdown blocks in one payload: 12,000 characters.