Markus

A small, fast, native macOS Markdown editor with GitHub-style preview.

What it does

Native macOS Markdown editor. Document-based: open .md / .markdown, edit, and preview with GitHub-flavored rendering (marked + highlight.js).

Requirements

• macOS 13+
• XcodeGen

Quickstart

brew install xcodegen
git clone https://github.com/nightmoose/Markus.git
cd Markus
xcodegen generate
open Markus.xcodeproj    # then Run (Cmd-R)

Build

xcodegen generate
open Markus.xcodeproj

Bundle id is com.nightmoose.markus. Signing: Automatic. Select your own team in Xcode, and change the bundle id in project.yml if you sign under a different team (also update set-default.swift).

Usage

Double-click any .md file, or File > Open. Edit on one side and see the rendered preview, with syntax-highlighted code blocks and light/dark themes. To make Markus the default app for Markdown, run swift set-default.swift --set; run it with no flag to see the current handler, optionally passing a .md path.

Layout

Sources/App          SwiftUI document + preview
Sources/Resources    CSS/JS preview bundle, app icon
project.yml          XcodeGen spec
make-icon.swift      Iconset helper
set-default.swift    Set/inspect the default Markdown handler

Bundled third-party code is listed in THIRD_PARTY_NOTICES.md.

License

MIT © 2026 NightMoose, Inc.