Beautiful Mermaid

Render Mermaid diagrams as beautiful SVGs or ASCII art. Ultra-fast, fully themeable, zero DOM dependencies. Built for the AI era.

When to Use

Use this skill when:

User sends Mermaid code blocks (```mermaid ... ```)
User asks to "render" or "visualize" a diagram
User wants terminal/ASCII output for diagrams
User needs themed diagrams (15 built-in themes)
User wants SVG output for rich UIs

Installation

npm install beautiful-mermaid
# or
bun add beautiful-mermaid
# or
pnpm add beautiful-mermaid

Quick Start

SVG Output (Default)

import { renderMermaid } from 'beautiful-mermaid'

const svg = await renderMermaid(`
  graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Action]
    B -->|No| D[End]
`)

ASCII Output (Terminal)

import { renderMermaidAscii } from 'beautiful-mermaid'

const ascii = renderMermaidAscii(`graph LR; A --> B --> C`)

Output:

┌───┐     ┌───┐     ┌───┐
│   │     │   │     │   │
│ A │────►│ B │────►│ C │
│   │     │   │     │   │
└───┘     └───┘     └───┘

Supported Diagrams

Type	Syntax	Description
Flowchart	`graph TD/LR/BT/RL`	All directions supported
State	`stateDiagram-v2`	State machine diagrams
Sequence	`sequenceDiagram`	Sequence/interaction diagrams
Class	`classDiagram`	Class inheritance diagrams
ER	`erDiagram`	Entity-relationship diagrams

Flowchart Example

```mermaid graph TD A[Start] --> B{Decision} B -->|Yes| C[Action] B -->|No| D[End] C --> D ```

Sequence Example

```mermaid sequenceDiagram Alice->>Bob: Hello Bob! Bob-->>Alice: Hi Alice! ```

Theming System

Built-in Themes (15)

import { renderMermaid, THEMES } from 'beautiful-mermaid'

// Use a built-in theme
const svg = await renderMermaid(diagram, THEMES['tokyo-night'])

// Available themes:
THEMES['zinc-light']
THEMES['zinc-dark']
THEMES['tokyo-night']
THEMES['tokyo-night-storm']
THEMES['tokyo-night-light']
THEMES['catppuccin-mocha']
THEMES['catppuccin-latte']
THEMES['nord']
THEMES['nord-light']
THEMES['dracula']
THEMES['github-light']
THEMES['github-dark']
THEMES['solarized-light']
THEMES['solarized-dark']
THEMES['one-dark']

Custom Theme (Mono Mode)

// Just two colors - the system derives everything
const svg = await renderMermaid(diagram, {
  bg: '#1a1b26',  // Background
  fg: '#a9b1d6',  // Foreground
})

Enriched Theme

const svg = await renderMermaid(diagram, {
  bg: '#1a1b26',
  fg: '#a9b1d6',
  line: '#3d59a1',    // Edge color
  accent: '#7aa2f7',  // Arrow heads
  muted: '#565f89',   // Secondary text
  surface: '#292e42', // Node fill
  border: '#3d59a1',  // Node stroke
})

Shiki Theme Compatibility

import { renderMermaid, fromShikiTheme } from 'beautiful-mermaid'
import { getHighlighter } from 'shiki'

const highlighter = await getHighlighter({ theme: 'vitesse-dark' })
const colors = fromShikiTheme(highlighter.getTheme('vitesse-dark'))
const svg = await renderMermaid(diagram, colors)

ASCII/Unicode Output

For terminal environments:

import { renderMermaidAscii } from 'beautiful-mermaid'

// Unicode (prettier, default)
const unicode = renderMermaidAscii(`graph LR; A --> B`)

// Pure ASCII (maximum compatibility)
const ascii = renderMermaidAscii(`graph LR; A --> B`, { useAscii: true })

// Custom spacing
renderMermaidAscii(diagram, {
  useAscii: false,
  paddingX: 5,          // Horizontal spacing
  paddingY: 5,          // Vertical spacing
  boxBorderPadding: 1,  // Inner padding
})

API Reference

renderMermaid(text, options?): Promise

Render Mermaid to SVG.

Options:

Option	Type	Default	Description
`bg`	string	`#FFFFFF`	Background color
`fg`	string	`#27272A`	Foreground color
`line`	string?	—	Edge color
`accent`	string?	—	Arrow heads, highlights
`muted`	string?	—	Secondary text
`surface`	string?	—	Node fill tint
`border`	string?	—	Node stroke
`font`	string	`Inter`	Font family
`transparent`	boolean	`false`	Transparent background

renderMermaidAscii(text, options?): string

Render Mermaid to ASCII/Unicode. Synchronous.

Options:

Option	Type	Default	Description
`useAscii`	boolean	`false`	Use ASCII instead of Unicode
`paddingX`	number	`5`	Horizontal node spacing
`paddingY`	number	`5`	Vertical node spacing
`boxBorderPadding`	number	`1`	Inner box padding

THEMES: Record<string, DiagramColors>

All 15 built-in themes.

fromShikiTheme(theme): DiagramColors

Extract diagram colors from Shiki theme.

Usage in ThinkFleet

Telegram Integration

For Telegram, render as SVG and send as photo:

import { renderMermaid } from 'beautiful-mermaid'

async function sendMermaid(message: string) {
  const blocks = extractMermaidBlocks(message)
  
  for (const block of blocks) {
    const svg = await renderMermaid(block.code, THEMES['tokyo-night'])
    // Send SVG as photo to Telegram
  }
}

Terminal/CLI Output

import { renderMermaidAscii } from 'beautiful-mermaid'

function printDiagram(code: string) {
  const ascii = renderMermaidAscii(code)
  console.log(ascii)
}

Performance

100+ diagrams in under 500ms
Zero DOM dependencies - pure TypeScript
Ultra-fast - no browser/Puppeteer needed

Comparison to Alternatives

Feature	beautiful-mermaid	mmdc
Dependencies	Zero DOM	Puppeteer
Speed	<500ms for 100+ diagrams	Slower
ASCII output	✅ Native	❌ No
Themes	15 built-in + Shiki	CSS
Size	Lightweight	Heavy

Example Workflow

Input:

Here is the system architecture:

\`\`\`mermaid
graph TD
  User --> LB[Load Balancer]
  LB --> API[API Server]
  API --> DB[(Database)]
  API --> Cache
\`\`\`

And the flow:

\`\`\`mermaid
sequenceDiagram
  participant U as User
  participant A as API
  U->>A: Request
  A-->>U: Response
\`\`\`

Action: Render both diagrams with appropriate theme.

Output: Send two SVG images with captions.

Resources

npm: https://www.npmjs.com/package/beautiful-mermaid
GitHub: https://github.com/lukilabs/beautiful-mermaid
Live Demo: https://agents.craft.do/mermaid

beautiful-mermaid