Mermaid Diagrams
Flowcharts, sequence diagrams, and Gantt charts render inline from standard mermaid code blocks.
Built for macOS Tahoe with Liquid Glass
The Markdown editor macOS deserved.
Open any .md file. See it beautifully rendered. Toggle to code view to edit. That's it.
AI agents write markdown. OpenMark makes it beautiful.
$9.99 $5.99 · Launch price · ends March 14
Not Obsidian. Not VS Code. Just Markdown.
Built by one developer who wanted a better way to open .md files.
What OpenMark is
- A file editor — opens .md files from Claude, ChatGPT, Cursor, and anywhere
- Native macOS with Liquid Glass — 9 MB
- Spotlight Indexing — search markdown content system-wide
- $5.99 launch price (reg. $9.99) — one-time purchase
- 100% offline — no account, no cloud
What OpenMark isn't
- A knowledge base or note-taking app
- An Electron wrapper at 350 MB
- A walled garden that hides your files
- A subscription that charges you monthly
- A service that holds your files hostage
Features
Everything you need. Nothing you don't.
LaTeX Math
Inline and display math equations render with KaTeX. Write $E=mc^2$ and see it beautifully typeset.
Liquid Glass
Built for macOS Tahoe with Apple's Liquid Glass design language. Feels like a first-party app.
Syntax Highlighting
Color-coded markdown syntax in code view. Headings, bold, italic, links, code — all highlighted.
Keyboard-First
⌘B bold, ⌘I italic, ⌘K link, ⌘E code — plus a full set of formatting shortcuts. Never touch the mouse.
Spotlight Indexing
Your markdown files are searchable in Spotlight. Find documents by content, not just filename — without opening the app.
Apple Intelligence
Built-in Writing Tools support. Rewrite, proofread, and summarize right from the editor.
Export Anywhere
Export to PDF, HTML, or copy as rich text. Paste formatted markdown into any app.
9 MB, Not 350 MB
A native Swift app, not an Electron wrapper. Launches instantly, uses minimal memory, and respects your Mac's resources.
Rendering
- Full markdown rendering (headings, bold, italic, links, images, tables, blockquotes, lists)
- Mermaid diagrams (flowcharts, sequence, Gantt, state, ER, pie)
- LaTeX math (inline and display)
- Syntax-highlighted code blocks (20+ languages)
- Interactive task list checkboxes
Editing
- Color-only syntax highlighting
- Line numbers
- Bracket and quote auto-pairing
- List continuation on Enter
- Keyboard shortcuts (⌘B, ⌘I, ⌘K, ⌘E)
- Find and replace (⌘F)
- Drag-and-drop images
- Apple Intelligence Writing Tools
Navigation
- Table of contents sidebar
- Command palette (⌘⇧P)
- Bidirectional scroll sync
- Scroll position preserved between views
Export
- Export to PDF
- Export to HTML
- Copy as rich text
- Copy as markdown
macOS Integration
- Spotlight Indexing for markdown content
- Quick Look extension (preview .md in Finder)
- App Intents & Shortcuts support
- File type registration (.md, .markdown, .mdown, .mkd, .mkdn)
- External file change detection
- iCloud document support
- Multiple windows
- Full VoiceOver accessibility
Design
- Liquid Glass toolbar (macOS Tahoe)
- Native SwiftUI interface
- System fonts (SF Pro + SF Mono)
- Adaptive light and dark mode
- Word, character, and line count
Ready to try it?
$9.99 $5.99 · Launch price
What people are saying
“I just got it, good work, I'll use it as the thinking notepad in a split screen mode with Claude so that we both can refer the same document and the prompts just point to the file.”
“Appreciate it! Great app all around”
“Bought it yesterday, love it so far!”
“Just got it, love it so far, super clean UI”
Document View
Beautiful rendered markdown
Open any .md file and see it rendered with gorgeous typography. Headings, tables, images, code blocks, blockquotes — everything looks beautiful. Double-click to switch to editing.
Markdown View
Precise editing with syntax highlighting
Toggle to code view for precise editing with syntax highlighting and line numbers. Bracket auto-pairing, list continuation, and keyboard shortcuts for bold, italic, links, and more.
Mermaid & Math
Diagrams and equations, just work
Mermaid diagrams and LaTeX math render inline — no plugins, no configuration. Everything works offline with bundled KaTeX and mermaid.js.
New to Markdown?
Markdown is a simple way to format text using plain characters like #, **, and -. It's used everywhere now — AI tools like ChatGPT and Claude write in it, developers use it for documentation, and it's the format behind README files on every software project.
OpenMark turns those plain-text symbols into a beautifully rendered document, instantly.
Pricing
Launch Sale · ends March 14
$5.99
$9.99 one-time purchase
- No subscription. No account. No cloud.
- Buy once, own forever.
- Free updates for the life of the app.
- Works completely offline.
- Available on the Mac App Store.
Requires macOS Tahoe (macOS 26) or later
FAQ
Common questions about OpenMark.
- Why did you build OpenMark?
I wanted a fast, native Mac app for opening and reading markdown files — and nothing that existed felt right. Either it was an Electron app that took three seconds to launch, or a full knowledge-base tool that wanted me to import my files into a vault. OpenMark is the simple markdown editor I wanted and couldn't find. Read the full story →
- Is OpenMark a subscription?
No. OpenMark is a one-time purchase of $9.99 on the Mac App Store. No recurring charges, no account required.
- Does OpenMark collect any data?
No. OpenMark has no analytics, no telemetry, no accounts, and no network requests. Your files stay on your Mac. See our privacy policy →
- What file types does OpenMark support?
OpenMark opens .md, .markdown, .mdown, .mkd, and .mkdn files. You can set it as your default app for markdown files in Finder.
- Does OpenMark require an internet connection?
No. OpenMark works completely offline. Mermaid diagrams and LaTeX math are rendered using bundled JavaScript — no CDN or internet required.
- How does OpenMark compare to other editors?
We've written detailed comparisons with the most popular alternatives:
- Does OpenMark support split view / side-by-side preview?
OpenMark uses a single-pane design. You toggle between a rendered document view and a code editing view. This keeps the interface clean and simple, with smooth animations between modes.
- What macOS version is required?
OpenMark requires macOS Tahoe (macOS 26) or later.