macOS 13+ · Mac App Store

The preview follows the exact line you write

A markdown editor built for the Mac. Write on the left and the preview stays on the same line on the right. Mermaid and PlantUML diagrams, math, and syntax highlighting render as you type.

Free · macOS 13 (Ventura) or later · Apple Silicon and Intel
MarkChartEditor window with the dark editor on the left and a light live preview on the right showing headings, a checklist, and a Swift code block
core features

Nothing interrupts the writing

Built so you never have to stop writing just to check how it looks.

Line-level scroll sync

The preview tracks the line you are looking at. Wheel, trackpad, and dragging the scrollbar itself all stay in step — no drift between the two panes.

Diagrams and math

Mermaid flowcharts, PlantUML sequence diagrams, KaTeX math, and syntax highlighting render directly in the preview. No extra tool to open.

Real macOS tabs

The same tabs you know from Safari and Finder. Cmd+T for a new tab, drag a tab out for a new window, Window > Merge All Windows to bring them back.

Outline, find and replace

Jump anywhere from the heading list (Shift+Cmd+O). Search runs in both the source and the rendered preview, with matches highlighted.

Auto save and change detection

Your file saves itself moments after you pause. If another app edits the same file, you are told and asked whether to reload it.

Export to PDF and HTML

Save exactly what you see in the preview as a PDF or an HTML file, diagrams and math included.

screens

Here is what it looks like

Light and dark themes can be chosen separately for the editor and the preview.

Mermaid and PlantUML source on the left rendered as flowcharts and sequence diagrams in the preview on the right

Type it, see it drawn

Mark a code block as mermaid or plantuml and the preview turns it into a diagram, non-Latin labels included.

One window with three documents open as tabs, the preview showing KaTeX formulas and a numeric table

Several documents side by side

Keep them in tabs and switch as you go. KaTeX formulas and tables render in the preview too.

Focus mode current paragraph only Typewriter mode cursor stays centred Images drag, drop, paste Tables pick the grid size Formatting keys ⌘B ⌘I ⌘K ⌘E Tab switching ⌘1 – ⌘9 Line numbers on or off Font and size your choice
quick look · 4 languages

In Finder too, and in your language

Press space in Finder

Select a markdown file in Finder, press the space bar, and the fully rendered document appears without opening the app. Available as an in-app purchase.

  • Mermaid and PlantUML diagrams intact
  • KaTeX math and syntax highlighting
  • Tables, checklists, and images as rendered

Four languages

Menus, settings, and alerts are all translated. Pick one in Settings > General; the default follows your system language.

  • 한국어
  • English
  • 日本語
  • 简体中文
privacy

What you write stays on your Mac

No account, no sign-in. Documents are never uploaded and no usage data is collected. The one exception is PlantUML: rendering a diagram sends that diagram code to a rendering service.

Read the privacy policy

faq

Frequently asked questions

Is it free?

The app is free. Only the Quick Look full preview — pressing space on a markdown file in Finder — is an in-app purchase.

Which macOS do I need?

macOS 13 (Ventura) or later. It runs on both Apple Silicon (M1/M2/M3) and Intel Macs.

Does it support Mermaid and PlantUML?

Yes. Mark a code block as mermaid or plantuml and the preview renders it as a diagram. KaTeX math and syntax highlighting are supported as well.

Are my documents uploaded anywhere?

No. Files stay on your Mac. There is no account, no sign-in, and no analytics. The single exception is PlantUML, where the diagram code is sent to a rendering service to produce the image.

Can I use it in a language other than Korean?

It ships in Korean, English, Japanese, and Simplified Chinese. Choose one in Settings > General; the default follows your system language. Relaunch the app to apply the change.

Can I make it the default app for .md files?

Yes. In Finder, right-click a .md file, choose Get Info, pick this app under Open with, then click Change All.

Can I save as PDF?

Use File > Export as PDF and you get exactly what the preview shows. Export as HTML is available too.

Why is it called MarkChartEditor on the App Store?

MarkChartEditor is the registered Mac App Store name. The source repository is named MarkdownEditor — same app.

Get it and start writing

Free on the Mac App Store.

Free · macOS 13 (Ventura) or later · Apple Silicon and Intel