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 · One purchase. Mac, iPhone, and iPad.
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 on Mac, iPhone, and iPad — 8 MB
- Spotlight Indexing — search markdown content system-wide
- $9.99 — one purchase gets Mac, iPhone, and iPad
- 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.
Writing Modes
Focus Mode dims everything except the current paragraph. Typewriter Mode keeps your cursor centered. Zen Mode hides all UI.
4 Editor Themes
Default, Nord, Solarized Dark, and One Dark. Applies to both rendered and code views.
iPhone & iPad
Universal Purchase — one $9.99 gets you Mac, iPhone, and iPad. Read and view markdown files anywhere.
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)
- Image paste (⌘V) and drag-and-drop
- Move lines up/down (⌥↑/⌥↓)
- Configurable tab width (2, 4, or 8 spaces)
- Word wrap toggle
- Apple Intelligence Writing Tools
Navigation
- Table of contents sidebar
- Command palette (⌘⇧P)
- Bidirectional scroll sync
- Scroll position preserved between views
- Focus Mode — dim all except current paragraph (⌘⇧F)
- Typewriter Mode — keep cursor centered (⌘⌃T)
- Zen Mode — hide all UI chrome (⌘⇧Z)
Export
- Export to PDF
- Export to HTML
- Copy as rich text
- Copy as markdown
Platform Integration
- Universal Purchase — Mac, iPhone, and iPad
- Spotlight Indexing for markdown content (macOS and iOS)
- Quick Look extension (preview .md in Finder)
- App Intents & Shortcuts support
- File type registration (.md, .markdown, .mdown, .mkd, .mkdn, .mdx)
- External file change detection
- iCloud document support
- Multiple windows (macOS)
- iPad split view with table of contents sidebar
- Home screen Quick Actions (iOS)
- Full VoiceOver accessibility
Design
- Liquid Glass toolbar (macOS Tahoe)
- 4 themes: Default, Nord, Solarized Dark, One Dark
- 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 · One-time purchase
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
$9.99
one-time purchase
- One purchase — Mac, iPhone, and iPad.
- No subscription. No account. No cloud.
- Buy once, own forever.
- Free updates for the life of the app.
- Works completely offline.
Requires macOS Tahoe (macOS 26) or iOS 18+
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 App Store. One purchase gets you Mac, iPhone, and iPad — no recurring charges, no account required.
- Does OpenMark work on iPhone and iPad?
Yes. OpenMark v1.2 added a full iOS companion app. It's a Universal Purchase — one $9.99 payment gets you the Mac editor and the iOS reader. The iOS app renders markdown, Mermaid diagrams, and LaTeX math with the same quality as the Mac version.
- Does OpenMark collect any data?
No. OpenMark has no analytics, no telemetry, no accounts, and no network requests. Your files stay on your devices. See our privacy policy →
- What file types does OpenMark support?
OpenMark opens .md, .markdown, .mdown, .mkd, .mkdn, and .mdx 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 are the system requirements?
OpenMark requires macOS Tahoe (macOS 26) or later on Mac, and iOS 18 or later on iPhone and iPad.