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New: Markdown Mode Now Available

The Fully Private Mermaid and Markdown Viewer Your Mac Deserves

Looking for a clean, simple Mac app to write and preview Mermaid diagrams and Markdown — fully offline, completely private, with built-in history? Need to zoom, pan, and go fullscreen like a whiteboard for your meeting? That's exactly why we built this.

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Mermaid diagram editor with live preview on Mac

Live Preview, Instant Feedback

Write Mermaid and Markdown code on the left, see your diagram render in real time on the right. Support for 20+ diagram types including flowcharts, sequence diagrams, Gantt charts, mind maps, ER diagrams, and more.

Mermaid + Markdown, One Editor

Switch to Markdown mode to write technical documentation with embedded Mermaid diagrams. Perfect for README files, design docs, and project wikis — all in one native app.

Meeting Presentation Powerhouse

Charts support free pan and zoom — zoom into specific details during meetings to walk your team through the data. No need for screenshots or slide decks. Just open the App and it becomes your whiteboard.

Everything You Need

Packed with thoughtful features for your daily workflow.

Smart History

Auto-saves up to 100,000 edit histories. Rename, favorite, and quick-switch between diagrams effortlessly.

Favorites

Mark your most-used diagrams for instant access. Never lose track of important work again.

4x PNG Export

One-click export at 4x resolution for crisp, print-ready diagrams. Perfect for presentations and documentation.

Fully Offline

Built-in Mermaid engine with zero internet dependency. Your data stays on your Mac, always private and secure.

Meeting Mode

Free pan and zoom on any diagram. Use it as a whiteboard during meetings — no extra slides needed.

Dark & Light Mode

Switch between dark and light themes to match your preference or time of day. Easy on the eyes, always.

What's New

We ship improvements constantly. Here are the latest updates.

v1.9 (12)

Edit Right in the Preview

  • Edit Mermaid text in place: Double-click text in the Mermaid preview to edit it in place. Your changes go straight into the code.
  • Visual diagram editing: Click a Mermaid node to add a next step, connect it, change its shape or delete it. Add messages and notes in sequence diagrams and topics in mindmaps, and move the selection with the arrow keys.
  • Edit in the Markdown preview: Double-click to edit in the Markdown preview, with a toolbar for bold, links, headings and lists. Check off tasks with a click.
  • Unsaved changes reminder: Files with changes you haven't saved show a * in the tab and history, and you're asked to save before leaving them.
  • No more blank windows: Opening files from Finder or the Dock no longer leaves extra blank windows.
  • What's New notice: A What's New notice appears the first time you open the app after an update.
v1.8 (11)

File Editing, Presentation & Export Upgrades

  • Open files directly: Supports Markdown and Mermaid files. Open them via drag and drop, with each file in its own tab.
  • Save to the original file: Press ⌘S to save back to the original file with its formatting preserved; tabs indicate unsaved changes.
  • Better for meeting presentations: Click a diagram to jump to its source code, diagrams automatically fit the window, and the view no longer goes blank on syntax errors.
  • Export & share: New “Copy as Image” and “Duplicate” options; Dark Mode now exports light-themed images.
  • Safer & more stable: Automatically removes unsafe content, plus multiple bug fixes.
v1.6 (10)

Multi-Tab Window Support

  • Show the window tab bar by default, letting you switch between multiple diagrams within the same window.
v1.5 (8)

Update default language

  • Updated the default language to English for better international accessibility.
v1.4 (6)

Exported SVG Support

  • Mermaid diagrams can now be exported as SVG
v1.3 (4)

Navigation, Search & Organization

  • Text search in Markdown preview to quickly find content
  • History categorization for better file organization
  • [toc] command in Markdown mode to generate a table of contents
  • Bidirectional scroll sync for Markdown editor and preview
  • Enhanced syntax highlight color blocks in Markdown editor
v1.2 (3)

UI Polish & Quality-of-Life Improvements

Collapsible sidebar for a cleaner workspace. Scalable font size in Markdown preview for meeting-ready presentations. New always-on-top window mode.

v1.1 (2)

Markdown Support

Not just Mermaid anymore — switch to Markdown mode, which also supports embedded Mermaid diagrams for dual-mode viewing.

v1.0 (1)

Mermaid Viewer v1.0

A Mermaid diagram viewer with history tracking, font size adjustment, and image export support.

Start Diagramming Today

No account needed. No internet required.

Download for Mac

macOS 13+ · Apple Silicon native · Under 30MB