Markdown to Slack: Why the Formatting Doesn't Always Survive the Copy-Paste
You've got a beautifully formatted README, a clean docs page, or a structured API response — all in standard Markdown. You paste it into Slack and get asterisks everywhere, literal hash symbols, and a table that's just a sad wall of pipes.
Not a bug. Just a format mismatch. Once you understand why it happens, fixing it is straightforward.
Slack Doesn't Use Markdown — It Uses "mrkdwn"
Slack has its own formatting syntax called mrkdwn — yes, without the "a." It's built specifically for Slack: making text look good inside the platform and hooking into features like @-mentions and channel references. It's not trying to be Markdown — it just looks that way at first glance.
Both systems let you write plaintext that renders as formatted text, but the syntax diverges in ways that'll catch you off guard.
The practical upshot: copy-pasting standard Markdown into Slack is a coin flip. Some things survive. A lot don't.
What's Different: A Syntax Breakdown
Bold, Italic, and Strikethrough
Standard Markdown uses **double asterisks** for bold. Slack uses *single asterisks*. That's the gotcha behind countless broken alert messages.
Paste **important deadline** into Slack and you'll see **important deadline** — asterisks and all.
| Format | Standard Markdown | Slack mrkdwn |
|---|---|---|
| Bold | **text** |
*text* |
| Italic | *text* or _text_ |
_text_ |
| Strikethrough | ~~text~~ |
~text~ |
| Inline code | `code` |
`code` |
| Code block | ```code``` |
```code``` |
| Link | [text](url) |
<url|text> |
The link format is unintuitive — URL comes first, then display text. The opposite of what you're used to.
What's Missing Entirely
Several standard Markdown features don't exist in mrkdwn: headers, tables, syntax-highlighted code blocks, images, horizontal rules, and task list checkboxes.
The heading gap is significant, especially for AI-generated output that leans on heading structure. In Slack, bold text is your best substitute for section titles. For tabular data, code blocks with manual spacing work — not pretty, but functional. For syntax highlighting, Slack's snippet feature is the right tool.