Mermalaid - The #1 Free Mermaid Diagram Editor | 100% Open Source & Free

Mermalaid is the premier free, open-source Mermaid diagram editor and chart creator. Create unlimited Mermaid diagrams, flowcharts, sequence diagrams, and more—completely free, no restrictions, no sign-ups required. The best free alternative to paid Mermaid editors.

🎯 Why Mermalaid? The Best Free Mermaid Editor

Looking for a free Mermaid editor? Tired of Mermaid diagram tools with limits, subscriptions, or hidden costs? Mermalaid is completely free and open source—no document limits, no premium features, no credit cards required.

Key Differentiators

• ✅ 100% Free - No restrictions, no limits, free forever (free as in free beer 🍺)
• ✅ Completely Open Source - Full source code available, modify as you need
• ✅ No Sign-Up Required - Start creating Mermaid diagrams instantly
• ✅ Unlimited Diagrams - Create as many Mermaid charts as you need
• ✅ Professional Features - Live preview, visual editor, syntax highlighting, SVG/PNG/ASCII export, Private Share Link
• ✅ Privacy-First - All data stays local, no cloud sync required
• ✅ Web & Desktop - Use in browser or download native macOS app

🚀 Quick Start - Create Your First Mermaid Diagram

Use Online (Web Version)

Visit Mermalaid to start creating Mermaid diagrams instantly in your browser—no installation needed.

Download Desktop App (macOS)

1. Download the latest release from GitHub Releases
2. Install the .dmg file
3. Start creating unlimited free Mermaid diagrams
4. 🏴‍☠️ IMPORTANT: Follow this step: Installing the Desktop App.

✨ Features - Professional Mermaid Editor, Zero Cost

Mermalaid provides professional-grade features typically found in paid Mermaid editors—all completely free:

Editor Features

• Monaco Editor with syntax highlighting for Mermaid code
• Live Preview with debounced updates (500ms) - See changes in real-time
• Visual Editor - Drag-and-drop flowcharts with React Flow; switch to visual mode for supported diagrams
• Real-time Syntax Validation - Instant error detection and feedback
• Auto-save to localStorage - Never lose your work
• Dark/Light Mode - Work in your preferred theme
• beautiful-mermaid Themes - Multiple themes (GitHub Light/Dark, Tokyo Night, Catppuccin, Dracula, Nord, and more) that style both diagrams and the app UI
• Toast Notifications - Clear feedback for actions (save, export, errors)
• AI Syntax Fix - Copy-pasted the diagram from somewhere but it has syntax errors? 🤖 Let AI fix it ✨ for you. (You will need an OpenAI API key, it's stored locally in your machine so it's only yours).

File Management

• Open Files - Import .mmd, .txt, or .md files with Mermaid code
• Save Diagrams - Export your Mermaid diagrams to local files
• Export Options:
  • SVG Export - Vector graphics for presentations and documents
  • PNG Export - Raster images for documentation and web use
  • ASCII Export - Unicode box-drawing for terminals (flowcharts, state, sequence, class, ER diagrams)
• Copy to Clipboard - Export code blocks ready for Markdown, GitHub, or documentation
• Private URL share - Copy private link puts the diagram in #v1.<payload> only (fragment, not query). The payload is compressed, encrypted locally with AES-GCM (Web Crypto), then base64url-encoded. There is no upload and no server sees the ciphertext in HTTP requests (fragments are not sent). Anyone who has the full link can decrypt it; treat links like secrets.

Mermaid Diagram Types Supported

Create unlimited diagrams of all types:

• Flowcharts (graph, flowchart)
• Sequence Diagrams (sequenceDiagram)
• Class Diagrams (classDiagram, classDiagram-v2)
• State Diagrams (stateDiagram, stateDiagram-v2)
• Entity Relationship Diagrams (erDiagram)
• User Journey (journey)
• Gantt Charts (gantt)
• Pie Charts (pie)
• Git Graphs (gitGraph)
• And More - Full Mermaid.js support

Cross-Platform Support

• Web Application - Works in any modern browser
• Native macOS App - Lightweight desktop application
• Static Hosting - Deploy anywhere (Vercel, Netlify, Appwrite Sites, etc.)

💻 Technical Excellence

Built with Modern Technologies

• Tauri - Lightweight, secure, native desktop framework (~10MB vs ~100MB+ Electron apps)
• React + TypeScript - Modern, type-safe UI development
• Monaco Editor - The same editor that powers VS Code
• beautiful-mermaid - Beautiful, themed Mermaid diagram rendering with customizable themes
• @xyflow/react - Visual editor for drag-and-drop flowchart editing

Why Tauri?

Mermalaid uses Tauri instead of Electron for a superior experience:

• 🚀 Much smaller app size (~10MB vs ~100MB+ for Electron)
• ⚡ Better performance using system webview instead of bundled Chromium
• 🔒 Enhanced security with Rust backend
• 💰 Lower memory usage - Runs efficiently on any machine
• 🎯 Better native integration - Feels like a real macOS app

📚 Use Cases - When to Use Mermalaid

Mermalaid is perfect for:

• Software Developers - Document architecture, workflows, and system designs
• Technical Writers - Create diagrams for documentation and tutorials
• Project Managers - Visualize project flows and processes
• Students - Create diagrams for assignments and presentations
• DevOps Engineers - Document infrastructure and deployment pipelines
• Anyone - Who needs to create Mermaid diagrams without limits or costs

🎨 Example Mermaid Diagrams

Try these examples in Mermalaid:

Flowchart Example

graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Action 1]
    B -->|No| D[Action 2]
    C --> E[End]
    D --> E

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Sequence Diagram Example

sequenceDiagram
    Alice->>Bob: Hello Bob, how are you?
    Bob-->>Alice: Great!

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Class Diagram Example

classDiagram
    class Animal {
        +String name
        +int age
        +eat()
    }
    class Dog {
        +bark()
    }
    Animal <|-- Dog

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🔧 Development & Installation

Prerequisites

• Node.js 18+
• Rust (Tauri will install automatically if not present)
• macOS (for building macOS apps)

Running in Development

# Install dependencies
npm install

# Run Tauri in development mode (desktop app)
npm run tauri:dev

# Or run web version only
npm run dev

This will:

1. Start the Vite dev server on http://localhost:5173
2. Launch Tauri with the development server (if using desktop)
3. Hot reload your React app

Building for Production

# Build web assets
npm run build

# Build macOS desktop app
npm run tauri:build

The built app will be in src-tauri/target/release/bundle/:

• .app file for macOS
• .dmg installer

Installing the Desktop App

Important: The app is currently unsigned (not code-signed). macOS may show a "damaged" warning when you first open it.

Recommended Installation Method:

# 1. Copy the app from the DMG to Applications
cp -R /Volumes/Mermalaid_*/Mermalaid.app /Applications/

# 2. Remove quarantine attribute
xattr -cr /Applications/Mermalaid.app

# 3. Open the app
open /Applications/Mermalaid.app

Alternative: System Settings

1. Open System Settings → Privacy & Security
2. Scroll down to see the blocked app message
3. Click "Open Anyway" next to the Mermalaid warning
4. Click "Open" in the confirmation dialog

⌨️ Keyboard Shortcuts

• ⌘N (Mac) / Ctrl+N (Windows/Linux): New diagram
• ⌘O / Ctrl+O: Open file
• ⌘S / Ctrl+S: Save file

🤝 Contributing

Mermalaid is open source and welcomes contributions! See CONTRIBUTING.md for guidelines.

Areas where contributions are especially welcome:

• Additional Mermaid diagram types
• Export formats (PDF, etc.)
• Platform support (Windows, Linux)
• Performance improvements
• Documentation and examples

📖 Documentation

• Contributing Guide - How to contribute to Mermalaid
• Project Structure - Codebase organization and file structure
• Deployment Guide - Deploy Mermalaid web version
• Appwrite Setup - Step-by-step Appwrite Sites setup
• Static Hosting - Hosting configuration details

🐛 Troubleshooting

Tauri won't start:

• Make sure Rust is installed: rustc --version
• Tauri will prompt to install Rust if missing
• Check that port 5173 is available for dev server

Build fails:

• Ensure you've run npm run build first
• Check that dist/ directory exists with built files
• On macOS, you may need to allow the app in Security & Privacy settings

App size concerns:

• Tauri apps are much smaller than Electron (~10MB vs ~100MB+)
• First build may take longer as Rust compiles dependencies

📄 License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

CC BY-NC-SA 4.0 - Free to use, modify, and share (non-commercial)

🌟 Why Choose Mermalaid Over Other Mermaid Editors?

Feature	Mermalaid	Other Tools
Cost	✅ 100% Free	❌ Free tier with limits, paid for unlimited
Open Source	✅ Yes, fully open	❌ Usually closed source
Document Limits	✅ Unlimited	❌ Often 3-5 documents max
Sign-Up Required	✅ No	❌ Usually required
Privacy	✅ Local storage only	❌ Cloud sync required
Export Options	✅ SVG, PNG, ASCII	✅/❌ Varies
Syntax Validation	✅ Real-time	✅/❌ Varies
Desktop App	✅ Native macOS	❌ Often web-only
Visual Editor	✅ Yes (flowcharts)	❌ Usually code-only

🎯 SEO Keywords & Search Terms

Mermalaid is optimized for these search terms:

• free mermaid editor
• mermaid diagram editor free
• open source mermaid editor
• free mermaid chart creator
• mermaid diagram tool free
• online mermaid editor free
• mermaid flowchart editor
• free mermaid diagram generator
• mermaid editor no sign up
• best free mermaid tool

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🔗 Share Mermalaid with others who need a completely free, open-source Mermaid editor.

💬 Have questions? Open an issue or check our documentation.

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Mermalaid - The #1 Free Mermaid Diagram Editor. Completely Open Source. 100% Free. Forever.