markdown-to-slack

Convert Markdown to Slack Block Kit JSON format.

Usage

$3

Install and use as command-line tool.

``bash
npm install -g markdown-to-slack

Using echo pipe

echo "# Hello World" | md2s

Full command name also available

echo "# Hello World" | markdown-to-slack
`

$3

Use as TypeScript/JavaScript library.

`typescript
import { MarkdownToSlack } from './source/module'

const markdown =

Title

Bold and italic text
- Item 1
- Item 2

const messages = MarkdownToSlack.convert(markdown)
console.log(JSON.stringify(messages, null, 2))
`

API

- MarkdownToSlack.convert(markdown: string): SlackMessage[]
- Returns array of Slack messages (split by 50-block limit or tables)

Mapping Table

| Markdown | Slack Block Kit | Notes |
|----------|----------------|-------|
| # Heading 1 | Header Block (auto-split if >150 chars) | H1 with visual separation |
| ## Heading 2 | Header Block (auto-split if >150 chars) | H2 with divider |
| ### Heading 3 | Header Block (auto-split if >150 chars) | H3 as header |
| #### Heading 4-6 | Section (bold) | H4-H6 as bold text |
| bold / __bold__ | Rich Text (bold) | Bold formatting |
| italic / _italic_ | Rich Text (italic) | Italic formatting |
| bold+italic | Rich Text (bold+italic) | Combined formatting |
| _text_ | Rich Text (bold+italic) | Alternative combined format |
| ~~strikethrough~~ | Rich Text (strike) | Double tilde strikethrough |
| ~strikethrough~ | Rich Text (strike) | Single tilde strikethrough |
| code | Rich Text (code) | Inline code |
| text | Rich Text Link | Hyperlink |
| - item / * item / + item | Rich Text List (bullet) | Unordered list |
| 1. item | Rich Text List (ordered) | Ordered list |
| - nested | Rich Text List (indent) | Nested lists (multi-level) |
| 5. item | Rich Text List (offset) | Custom start number |
| - [ ] task / - [x] task | Rich Text List | Task checkboxes (stripped) |
| ``code` | Rich Text Preformatted | Code block (no language specified) |
| `lang` | Context Block + Rich Text Preformatted | Code block with language context |
| > quote | Rich Text Quote | Blockquote |
| --- / * / ___ | Divider Block | Horizontal rule |
| Markdown table | Context Block + Table Block | Context shows row count, tables (max 1 per message) |
| Table cells with markdown | Rich Text Cell | Inline formatting in cells |
|
/
| \n | Line break (converted before parsing) |
| :emoji: | Emoji | Emoji shortcode |
| !alt / | Image Block | Alt text as title, Slack file URL supported |
|

| Divider section | Collapsible section with dividers |

Messages are automatically split due to Slack limitations.
- Maximum 50 blocks per message
- Maximum 1 table per message
- Tables are isolated into separate messages
- Header text exceeding 150 characters is automatically split into multiple headers