Where Markdown Works in Slack

Almost every “why is my Slack formatting broken” question is really this question. Slack has three places text gets formatted, and each one parses a different syntax.

Slack Text Formatting (mrkdwn)

This is the syntax that makes Slack different from every other Markdown. Because most renderers get it wrong, the right-hand panel below shows what Slack actually displays rather than a Markdown preview.

*bold text*

_italic text_

~strikethrough~

*_bold italic_*

Standard Markdown in Slack: the markdown block

Slack introduced a Block Kit markdown block on 3 February 2025 and widened it on 6 March 2026 with tables, task lists, dividers, syntax-highlighted code blocks and variable-sized headers. It takes standard Markdown and does the conversion to Slack's internal format itself — so inside one, **bold** is correct and *bold* means italic, exactly backwards from mrkdwn.

Slack's own stated reason for it is AI: when an LLM hands your app Markdown, a markdown block lets Slack translate it instead of you writing a converter. If you are formatting model output for Slack, this is the block to reach for — see our Markdown for AI guide for the wider pattern.

{
  "blocks": [
    {
      "type": "markdown",
      "text": "## Deploy finished\n\n- [x] tests green\n- [ ] changelog\n\n| env | status |\n| --- | ------ |\n| prod | green |"
    }
  ]
}

**bold**, *italic*, ~~strikethrough~~ and `inline code`

# Header 1
## Header 2
### Header 3

- first item
- second item
  - nested item

1. first step
2. second step

- [x] shipped the release notes
- [ ] update the changelog

| Environment | Status |
| ----------- | ------ |
| production  | green  |
| staging     | red    |

Above the line

---

Below the line

Links

mrkdwn masks links with angle brackets and a pipe rather than [text](url). Both forms exist on Slack — which one is correct depends on the surface, and getting it wrong is the difference between a link and a line of visible punctuation.

<https://slack.com|Slack>

<https://slack.com>

<mailto:me@example.com|Email me>

[Slack](https://slack.com)

Mentions and Special Tokens

Mentions are IDs wrapped in angle brackets, not display names. The composer autocompletes @name into the right ID for you; an API message has to arrive with the ID already in it, or it is just text and nobody gets notified. Slack recommends the explicit form precisely because names change.

<@U012AB3CD>

<#C123ABC456>

<!subteam^S0NHM1FH4>

<!here>

<!channel>

<!date^1392734382^{date_short} at {time}|Feb 18, 2014 at 6:39 AM>

Lists

Lists exist on two of Slack's three surfaces. In the composer, type * or 1. followed by a space and Slack builds a rich-text list as you go. In a markdown block, ordinary - item syntax renders properly. Plain mrkdwn has no list syntax at all — Slack's docs suggest mimicking one with hyphens and newlines, which is exactly as good as it sounds.

- first item
- second item
- third item

1. first step
2. second step
3. third step

Headings

Headings are the thinnest part of Slack formatting. There is no heading button in the composer toolbar and no keyboard shortcut for one; mrkdwn leaves # as a literal character; and a markdown block does accept # through ###### but renders every level at the same size, so the hierarchy you write is not the hierarchy readers see.

For an app that needs one visually distinct title, the Block Kit header block is the reliable answer — it is a structural block rather than a piece of text formatting.

{
  "blocks": [
    {
      "type": "header",
      "text": { "type": "plain_text", "text": "Deploy finished" }
    },
    {
      "type": "section",
      "text": { "type": "mrkdwn", "text": "Shipped by <@U012AB3CD> at *09:41*." }
    }
  ]
}

Note the mixture: a header block takes plain_text only, so no formatting is parsed inside it, while the section below it is mrkdwn and so uses single asterisks. See Markdown headings for how the syntax behaves everywhere else.

Slack Markdown Tables

“Slack does not support tables” was true for a decade and is now out of date. There are three answers, depending on who is sending the message.

| Service | Owner | Status |
| ------- | ----- | ------ |
| api     | Dana  | green  |
| web     | Ravi  | amber  |

| Left | Center | Right |
| :--- | :----: | ----: |
| a    | b      | c     |

Need the pipe syntax itself? Our Markdown tables guide covers alignment and escaping, and the table generator builds one you can drop straight into a markdown block.

Quotes and Code Blocks

These are the constructs where all three surfaces agree, with one exception: a language identifier on a code fence is honoured inside a markdown block and silently discarded everywhere else.

> This line is quoted.

> Line one of the quote.
> Line two continues it.

`inline code` stays monospaced

```
function hello() {
  return "world";
}
```

function hello() {
  return "world";
}

```python
print("hello")
```

print("hello")

The Composer: Shortcuts and the Markup Preference

By default the composer is WYSIWYG — you format with the toolbar or a shortcut and see the result as you type. Slack also ships a preference that turns typing into markup instead: click your profile picture, then Preferences → Advanced, and check “Format messages with markup” under Input options. Formatting is then applied only after the message is sent.

It has two side effects Slack documents and people rarely expect: automatic list formatting is turned off, and pasted messages arrive as plain text. That last one is a feature if you paste code and snippets all day.

Escaping

Because mrkdwn builds links, mentions and date tokens out of angle brackets, three characters have to be escaped as HTML entities when an app sends mrkdwn. The composer handles this for you; a webhook payload does not.

Inside a markdown block the rule is the ordinary Markdown one instead: a backslash before the character, so \*not italic\* keeps its asterisks. And to switch parsing off wholesale, set mrkdwn: false on a message, use a plain_text object inside a block, or set verbatim: true to keep formatting but stop Slack auto-linking names.

Common Mistakes

Every one of these comes from applying one surface's rules to another.

Slack Formatting Quick Reference

Every syntax on one screen, with the surface it belongs to.

Frequently Asked Questions