markdown-to-slack

Convert Markdown to Slack Block Kit JSON format.

Usage

CLI

Install and use as command-line tool.

npm install -g markdown-to-slack

# Using echo pipe
echo "# Hello World" | md2s

# Full command name also available
echo "# Hello World" | markdown-to-slack

Library

Use as TypeScript/JavaScript library.

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](url) | 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 | | <br> / <br/> | \n | Line break (converted before parsing) | | :emoji: | Emoji | Emoji shortcode | | ![alt](url) / <img> | Image Block | Alt text as title, Slack file URL supported | | <details><summary> | 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