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Markout

A modern, native macOS Markdown editor for Apple Silicon — the spiritual successor to the unmaintained MacDown.

Built with SwiftUI + TextKit + WKWebView. Everything runs offline — the syntax, math, and diagram engines are vendored, no CDN. MIT licensed.

Download

Homebrew

brew install --cask maxmilian/tap/markout

Once installed, open any file from the terminal:

markout path/to/file.md

Or download the .dmg

⬇ Download the latest release — or build from source.

1. Open the downloaded Markout-*.dmg and drag Markout into your Applications folder.
2. First launch only: right-click Markout.app → Open → Open.

Markout is ad-hoc signed but not notarized by Apple, so macOS shows a Gatekeeper warning the first time. Right-click → Open tells macOS to trust it. If double-clicking still refuses to open it, clear the quarantine flag once in Terminal:

xattr -cr /Applications/Markout.app

Requires macOS 14 or later (Apple Silicon recommended).

Why Markout

Markout is built for people who still want a fast, native Markdown editor on macOS: open a file, write in plain text, see the rendered result immediately, and export without sending the document to a hosted service.

It focuses on:

• Native macOS behavior instead of a web-app shell
• Offline rendering for Markdown, code highlighting, math, and diagrams
• A familiar split editor / preview workflow
• A small, understandable Swift codebase that is easy to improve

Features

Editing

• Split editor + live preview with a 150 ms debounced render
• Markdown syntax highlighting with switchable editor color themes
• Automatic list continuation, image paste/drop (saved beside the document)
• Find & replace, optional line-number gutter, soft wrap toggle
• Formatting toolbar and Format menu (bold ⌘B, italic ⌘I, link ⌘K, headings, quote, list) — all undoable

Preview

• GitHub-Flavored Markdown via cmark-gfm
• Syntax-highlighted code (highlight.js)
• TeX math (KaTeX) — inline $…$ and display $$…$$
• Diagrams (Mermaid)
• Editor ↔ preview scroll sync
• Switchable preview themes + your own custom CSS
• Light/dark mode that follows the system

Output & editing aids

• Export to standalone HTML (CSS inlined) or PDF (matches the live preview)
• Table of contents (insert into the document or browse in a sidebar)
• YAML front matter parsing
• Live word / character / reading-time count

Preferences (⌘,) — editor font size, editor theme, soft wrap, line numbers, preview theme + custom CSS, word-count visibility.

Requirements

• macOS 14 or later
• Apple Silicon Mac recommended
• Xcode
• XcodeGen

Building

brew install xcodegen
xcodegen generate
xcodebuild -project Markout.xcodeproj -scheme Markout -destination 'platform=macOS' build

Run the tests:

xcodebuild test -project Markout.xcodeproj -scheme Markout -destination 'platform=macOS'

See CLAUDE.md for architecture notes and docs/superpowers/ for the design specs and implementation plans.

Project structure

Sources/Markout/
├── App/          # SwiftUI app shell and document actions
├── Document/     # Markdown document model, front matter, pasted assets
├── Editor/       # TextKit editor, syntax highlighting, formatting helpers
├── Export/       # HTML and PDF export
├── Preview/      # WKWebView preview and scroll sync
├── Render/       # Markdown rendering, HTML template, preview themes
└── Settings/     # Preferences, editor themes, appearance resolution

Vendored preview assets live in Resources/PreviewAssets/, and tests live in Tests/MarkoutTests/.

Status

The four-phase roadmap is complete:

• ✅ P1 — Core MVP: split editor + live preview, GFM rendering, syntax highlighting, open/save, dark mode.
• ✅ P2 — Rich content: code highlighting, KaTeX math, Mermaid diagrams, scroll sync, preview themes.
• ✅ P3 — Output & editing: export HTML/PDF, TOC, front matter, image paste, find & replace.
• ✅ P4 — Polish: Preferences, editor themes, word count, formatting toolbar.

Localization

This README is available in:

• English
• 繁體中文
• 简体中文
• 日本語
• 한국어

Translations should preserve the same technical meaning as the English README. If a feature changes, update the English README first, then update the translations in the same pull request when practical.

Contributing

Contributions are welcome: bug fixes, editor improvements, rendering fixes, export polish, documentation, tests, and translations.

Before opening a pull request:

1. Keep changes focused and consistent with the existing SwiftUI / TextKit / WKWebView architecture.
2. Run xcodegen generate if project.yml changed.
3. Run xcodebuild test -project Markout.xcodeproj -scheme Markout -destination 'platform=macOS'.
4. Update README or localized README files if the user-facing behavior changed.

See CONTRIBUTING.md for the full contribution guide.

Acknowledgements

Markout owes a debt to MacDown, the Markdown editor I relied on for years. MacDown is no longer maintained, so Markout is a fresh, fully native rebuild for modern Apple Silicon macOS — carrying that same fast, plain-text, offline spirit forward. Thank you to the MacDown authors.

License

Released under the MIT License. © 2026 maxmilian