A minimal macOS Markdown editor and viewer. Clean rendering, inline editing, and live preview — no bloat.
- Three view modes — view-only, split (editor + preview), and edit-only, cycled with Cmd+E
- Live preview — edits render responsively in the side-by-side split view
- Syntax highlighting — incremental highlighting for headings, bold, italic, links, code blocks, blockquotes, and lists
- Scroll sync — bidirectional scroll synchronization between editor and preview
- Markdown formatting — Bold (Cmd+B), Italic (Cmd+I), Link (Cmd+K)
- Secure GitHub-flavored rendering via marked.js and DOMPurify
- Sandboxed local resources — relative images and links work after one persisted folder authorization
- Dark Mode — automatic (system), light, or dark via View > Appearance
- Print — Cmd+P prints the current document from any view mode with paginated A4 output
- Context-aware zoom — Cmd+/Cmd- targets the active pane: preview in view mode, editor font in edit mode, focused pane in split mode
- New files — Cmd+N creates a blank Markdown document
- Native file handling — Open, Save, Recent Files, drag & drop
- About 1.5 MB total — no Electron or external runtime
| Metric | Value |
|---|---|
| App size | ~1.5 MB |
| Download (zip) | ~431 KB |
| Cold start | < 50 ms |
| Memory | ~112 MB |
Download the latest signed DMG from Releases or build from source:
brew install xcodegen
xcodegen generate
xcodebuild -scheme MDViewerPlus -configuration Release buildCreate a local release config from .release.env.example, then run:
scripts/release_macos.shThe GitHub release workflow builds a signed, notarized DMG on v* tags. Configure these repository secrets first:
MACOS_CERTIFICATE, MACOS_CERTIFICATE_PWD, APPLE_ID, APPLE_TEAM_ID, and APPLE_APP_PASSWORD.
| Action | Shortcut |
|---|---|
Cmd P |
|
| Toggle View Mode | Cmd E |
| Bold | Cmd B |
| Italic | Cmd I |
| Link | Cmd K |
| Save | Cmd S |
| New File | Cmd N |
| Reload | Cmd R |
| Zoom In | Cmd + |
| Zoom Out | Cmd - |
| Actual Size | Cmd 0 |
| System Appearance | Cmd Shift 0 |
| Light Mode | Cmd Shift 1 |
| Dark Mode | Cmd Shift 2 |
| Library | Version | License | Purpose |
|---|---|---|---|
| marked | 15.0.7 | MIT | Markdown → HTML parsing |
| DOMPurify | 3.4.12 | Apache-2.0 OR MPL-2.0 | HTML sanitization |
No Swift package dependencies or third-party native frameworks. JavaScript dependencies and their license notices are bundled with the app.
Release builds use the macOS App Sandbox and Hardened Runtime. Rendered HTML is sanitized, remote embedded resources are blocked, and external links open in their default app.
Relative images and local links require access to the Markdown document’s folder. MDViewer+ asks once, stores an app-scoped security bookmark, and limits WebKit reads to raster images inside that authorized folder.