A native macOS Markdown editor — a ground-up Swift / SwiftUI rewrite built on TextKit 2, a modular Swift package core, and a modern SwiftUI shell.
Status: early development. Foundations, file/format core, workspace shell, native window tabs, the TextKit 2 editor, tree-sitter highlighting, the theme system, a native Markdown parser, a block-sliced native preview, and the content browser — a heading outline of the active document in the sidebar, with reorderable/persisted sidebar sections (EPIC-00 → EPIC-08) — are in place. Performance numbers are package-level, not yet full-app-path measurements.
- macOS 26.0 or later
- Xcode 26 (Swift 6.2 toolchain, strict concurrency)
- XcodeGen — the
.xcodeprojis generated, not committed
MacDown2/
├── MacDown2/ # App target (SwiftUI shell)
├── MacDown2CLI/ # `macdown2` command-line tool
├── MacDown2UITests/ # XCUITest target
├── Packages/MacDownKit/ # Swift package — all logic lives here
│ └── Sources/
│ ├── FileCore # FileStore, FileFormat registry, document lifecycle
│ ├── Workspace # Per-window model + session restore (native NSWindow tabs)
│ ├── EditorCore # NSTextView + TextKit 2 editor
│ ├── Highlighting # Tree-sitter engine (markdown/json/html), Neon-backed
│ ├── Themes # Theme model + Tomorrow Light/Dark, live switching
│ ├── MarkdownEngine # Native swift-markdown parser + parse session store
│ ├── Preview # Block-sliced native Textual preview + scroll sync
│ ├── OutlineUI # Heading outline: tree, selection, identity remap, controller
│ ├── FileTree / AppSettings / ExportService # stubs for E09/E13/E12
│ └── …
├── Packages/TreeSitterMarkdown # Vendored markdown + markdown-inline grammars
└── project.yml # XcodeGen project definition
planning/ # Epic specs and implementation plans
legacy-reference/ # Legacy ObjC MacDown — read-only porting source
# 1. Logic package — build + test (all unit tests live here)
cd MacDown2/Packages/MacDownKit
swift build
swift test
# 2. Generate the Xcode project
cd ../..
xcodegen generate
# 3. Build the app and the CLI
xcodebuild -project MacDown2.xcodeproj -scheme MacDown2 -destination 'platform=macOS' build
xcodebuild -project MacDown2.xcodeproj -scheme macdown2 -destination 'platform=macOS' buildswiftformat --lint MacDown2
swiftlint lint --strict MacDown2CI (.github/workflows/ci.yml) runs the lint, package tests, and app/CLI builds
on every push and PR to master.
Development is organised into epics, each tracked as a GitHub issue with a spec in
planning/epics/ and a detailed implementation plan in
planning/. See planning/MIGRATION_PLAN.md
for the overall plan.
MacDown 2 is free and open-source software, released under the MIT License.
It is an open-source fork and successor of MacDown,
the original macOS Markdown editor by Tzu-ping Chung and contributors (also MIT-licensed).
The original copyright notice is retained in LICENSE.