A fast, native macOS Markdown editor that does one thing well.
Edit Markdown with a beautiful live preview — calm, local, folder-based.
No cloud, no accounts, no plugins. Your files stay on your machine.
Features · Installation · Shortcuts · Build · Report a bug · Buy me a coffee
Most Markdown apps want to be a publishing platform, an IDE, or a second brain. Glassmark wants to be the calmest, fastest way to write Markdown and see it rendered as you type. Open a folder, browse your .md files in a sidebar, edit on the left, watch the preview keep pace on the right. That's it — and it's polished to a shine.
Everything renders natively and offline: code highlighting, math, and diagrams are vendored into the app, so nothing is fetched from the network and your documents never leave your Mac.
Syntax-highlighted code (highlight.js) and rendered math (KaTeX) — all offline.
Mermaid diagrams and GFM tables, rendered live as you type.
| ⚡ Live preview | Updates as you type — debounced, flicker-free, scroll position preserved. |
| Scroll either pane in split mode and the other follows to the same source line. | |
| 🎨 GitHub-flavored Markdown | Headings, bold/italic/ |
| 🌈 Offline rich preview | Syntax-highlighted code (highlight.js), math (KaTeX $…$ / $$…$$), and diagrams (Mermaid) — all bundled, nothing fetched. |
| ✍️ Editor that feels alive | In-editor syntax highlighting, auto-pairing, automatic list continuation, and Tab-to-next-cell in tables. |
| 🧘 Calm-writing modes | Focus mode dims everything but the current paragraph; typewriter scrolling keeps your line centered. |
| 🗂️ Outline panel | Jump to any heading, with the current section highlighted as you scroll. |
| 🎭 Themes + custom CSS | System, Sepia, High Contrast, and Dark preview themes — plus your own stylesheet. |
| 📤 Export | One-click export to HTML or PDF. |
| 🪟 Multiple workspaces | Remembered folders with security-scoped bookmarks, a workspace rail, and per-workspace colors. |
| 🧰 Full file management | Create, rename, duplicate, cut/copy/paste, drag-to-move, delete-to-Trash, reveal in Finder. |
| 🔎 Quick Open & Find | Fuzzy file switching (⌘P) and the native find bar (⌘F). |
| 💾 Autosave & session restore | Optional autosave; reopens the files you had open per workspace. |
| 🧮 Live stats | Word, character, and line counts plus estimated reading time. |
Built with SwiftUI and an AppKit NSTextView editor, a WKWebView preview, and a dependency-free Markdown renderer that escapes all input and blocks unsafe URL schemes.
🍎 Coming soon to the Mac App Store. In the meantime, build from source (it takes under a minute).
# Requirements: macOS 15+, Xcode 26, and XcodeGen (brew install xcodegen)
git clone https://github.com/nerkza/GlassMark.git
cd GlassMark
xcodegen generate
open GlassMark.xcodeproj # then ⌘R, or use the helper belowOr build and launch from the command line:
script/build_and_run.shThe Mac App Store build updates itself automatically. The direct-download build (notarized Releases) checks GitHub for a newer version on launch and offers to open the download page — toggleable in Settings → General, and it sends no personal data. Maintainers cut a release with script/release.sh (see the script header for the one-time signing/notarization setup).
| Action | Shortcut |
|---|---|
| New Markdown file | ⌘N |
| Open workspace | ⇧⌘O |
| Quick Open | ⌘P |
| Save | ⌘S |
| Find | ⌘F |
| Refresh workspace | ⌘R |
| Toggle outline | ⌥⌘0 |
| Focus mode | ⌃⌘F |
| Bold / Italic / Inline code | ⌘B / ⌘I / ⌘E |
| Strikethrough | ⇧⌘X |
| Insert link | ⌘K |
| Heading 1–3 | ⌃⌘1 / ⌃⌘2 / ⌃⌘3 |
| Export as HTML / PDF | File menu |
Glassmark is generated with XcodeGen from project.yml, so the .xcodeproj is reproducible. After editing project.yml, regenerate it:
xcodegen generateBuild and run the test suite:
xcodebuild -project GlassMark.xcodeproj -scheme GlassMark -configuration Debug -derivedDataPath DerivedData build
xcodebuild -project GlassMark.xcodeproj -scheme GlassMark -derivedDataPath DerivedData test- SwiftUI app shell built around a
NavigationSplitView— workspace rail + file tree, editor/preview detail, and an outline inspector. - AppKit
NSTextVieweditor bridge for syntax highlighting, list continuation, auto-pairing, and the find bar. WKWebViewpreview using a persistent HTML shell updated via JavaScript (no full reloads), kept scroll-synced to the editor by source line.- Dependency-free
MarkdownHTMLRendererproducing escaped, sanitized HTML. - Vendored web assets (highlight.js, KaTeX, Mermaid) served to the preview over a custom
WKURLSchemeHandler, so the preview is fully offline. - Clear separation of stores (workspace, document, command, preferences) and services (file tree, persistence, rendering, export).
Glassmark is at its 1.0 milestone. Things on the horizon (kept in scope — no PKM, cloud, or plugins):
- Image paste/drag that saves into the workspace
- On-demand table column alignment
- Incremental preview DOM updates
- Larger-workspace performance profiling
Issues and pull requests are welcome. Glassmark deliberately stays narrow — a fast, beautiful Markdown preview editor — so the best contributions sharpen that core rather than broadening scope. Please run the test suite before opening a PR.
Glassmark is free and MIT-licensed. If it's found a place in your writing, you can support its development:
Starring the repo helps too — thank you. ☕️
Glassmark is released under the MIT License.
- highlight.js — code syntax highlighting
- KaTeX — math rendering
- Mermaid — diagrams
- XcodeGen — project generation