MarkDownEditor

MarkDownEditor is a Markdown viewer and editor for Windows 10 and 11. Set it as the default app for .md files and they open in a rendered view from Explorer. It is available as an installer or a portable ZIP and does not require an account or collect telemetry.

한국어 · English · 日本語 · 简体中文 · 繁體中文 · Español · Français · Deutsch · Русский · Português (Brasil)

Download from GitHub Releases

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Why this exists

I built MarkDownEditor because opening a Markdown file on Windows often meant starting a full code editor or using a browser extension. This app is meant to behave more like Notepad: double-click a file to read it, then press Ctrl+E if you need to edit it.

• The installer adds Start menu and Open With entries for the current user.
• The portable package keeps its settings and cache beside the executable when that folder is writable. It falls back to %TEMP%\MarkDownEditor for read-only locations.
• Rendering and editing happen locally. The only routine network request is an anonymous check for new GitHub releases.
• The project is released under the MIT license.

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Features

Reading

• Double-click to open — set it as the default .md handler and Explorer does the rest.
• One window, many tabs — open twenty files and you get twenty tabs, not twenty windows. Tabs reorder by drag & drop and cycle with Ctrl+Tab.
• Drag & drop — drop .md / .txt files onto the window to open them as tabs.
• GitHub-style rendering — headings, tables, task lists, blockquotes, and code, styled to match what you see on GitHub.
• Syntax highlighting — fenced blocks with a language tag (```cs, ```bash) get colored. Bundled offline, theme-aware.
• Mermaid diagrams — the same ```mermaid syntax GitHub and GitLab use: flowcharts, sequence, gantt, state. Bundled offline, theme-aware.
• Table-of-contents sidebar — toggled with ☰, with scroll-spy highlighting of the section you are reading.
• Document links — .md opens in a new tab, web links in your browser, folders in Explorer, and pdf / docx / xlsx / hwp in their default apps. Cross-document anchors (doc.md#section) are supported.
• Back / Forward — toolbar ← →, Alt+← / Alt+→, or mouse buttons 4 and 5. Scroll position is remembered per document.
• Local images — relative and absolute image paths (![](diagram.png)) resolve automatically. Click any image to view it full-screen.
• Keyboard-first — scroll with PageUp / PageDown / arrows / Home / End the moment the app launches, no click needed.
• Korean encoding detection — BOM-less CP949 / EUC-KR files open correctly alongside UTF-8.

Writing

• Edit ↔ Preview in one keystroke — Ctrl+E, with scroll position synchronized between the two modes.
• Formatting bar — buttons for bold, italic, strikethrough, headings, lists, quotes, code, links, tables, and dividers. Changes remain undoable with Ctrl+Z.
• Find and replace — Ctrl+F works in both preview (all matches highlighted) and edit mode; Ctrl+H replaces, with case sensitivity and Replace All.
• Paste screenshots — Ctrl+V an image while editing and it is saved into an images/ folder next to the document, with the link inserted for you.
• Export to PDF — one button, or Ctrl+P, turns the rendered preview into a PDF.
• Auto-reload on external change — if your IDE or another editor saves the open file, the tab refreshes automatically. Your unsaved edits are never silently overwritten.
• Auto-backup and crash recovery — unsaved changes are snapshotted every 30 seconds and offered back to you after an unexpected shutdown.
• Session restore — launch without a file and your previous tabs come back. Recent documents are one click away under 🕘.

Comfort

• Dark and light themes — including the Windows title bar. Remembered across runs.
• 10 UI languages — 한국어, English, 日本語, 简体中文, 繁體中文, Español, Français, Deutsch, Русский, Português (Brasil). Follows your OS language by default; switch anytime from 🌐.
• Compact chrome — tabs and tools live in a custom title bar, Notepad-style.
• Document zoom — Ctrl+Wheel changes preview and editor text without enlarging the app chrome. Click the percentage or press Ctrl+0 to reset; the level is remembered across runs.
• Shortcut reference — click the keyboard icon or press Ctrl+/ to see the main shortcuts without leaving the document.
• Per-tab position — scroll position and editor caret position are restored when you switch tabs.
• In-app updates — a red dot appears next to the version when a new release is available. Choose Update to download and install the matching package.

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Screenshots

Document preview	Language and version menu

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Installation

Both packages are for Windows 10 version 1809 or newer / Windows 11, x64. Neither requires administrator rights.

Package	Best for	Approximate download	Runtime and data
Windows installer	Normal daily use	45 MB	Installs per-user, uses automatically serviced Evergreen WebView2, adds Start menu and Open With entries. Data is under %LOCALAPPDATA%\MarkDownEditor. Internet is needed only if WebView2 is not installed; Setup fails clearly if the prerequisite cannot be installed.
Portable ZIP	USB, offline and no-install use	325 MB	Includes a fixed WebView2 runtime. Data stays in WebView2Data/ beside the app when writable.

All releases · Latest release notes · Full changelog

Portable setup

Extract the folder anywhere you can write to: C:\Tools\MarkDownEditor, your Desktop, a USB stick — it does not matter. Then run MarkDownEditor.exe.

The folder holds MarkDownEditor.exe plus web/ (the UI), Runtime/ (the bundled WebView2), and WebView2Data/ (cache). Keep them together and you can move, copy or carry the whole thing anywhere.

The blue SmartScreen dialog on first run is expected. The executable is not code-signed, so Windows shows "Windows protected your PC". Click More info → Run anyway. It only appears once. If you would rather build it yourself, see the separate development guide.

Make it the default app for .md files

Once this is set, double-clicking any Markdown file in Explorer opens it rendered, instantly.

1. Right-click any .md file in Explorer
2. Open with → Choose another app
3. Select MarkDownEditor — the installer registers it automatically; for the portable package, use Choose an app on your PC and select MarkDownEditor.exe
4. Tick Always use this app to open .md files, then OK

The same works for .markdown and .txt if you want them handled too.

Updating

On startup the app anonymously checks GitHub Releases and puts a red dot next to the version when a newer build exists. Click the version → Update. The selected asset's URL, size, SHA-256 digest, structure and version are verified before the app closes. Portable copies replace their payload atomically; installed copies run the next per-user installer. Settings and session data are preserved.

Uninstalling

• Installed edition: use Settings → Apps → Installed apps → MarkDownEditor → Uninstall. Program files, shortcuts and MarkDownEditor's own Open With registrations are removed; user data under %LOCALAPPDATA%\MarkDownEditor is preserved for safe reinstall or can be deleted manually.
• Portable edition: delete its folder. If it ever ran from a read-only location, also remove %TEMP%\MarkDownEditor to erase fallback settings and cache.

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Keyboard shortcuts

Key	Action
Ctrl+O	Open (multi-select supported)
Ctrl+N	New document tab
Ctrl+S	Save
Ctrl+P	Export as PDF
Ctrl+E	Toggle edit / preview
Ctrl+F	Find — works in preview and edit mode
Ctrl+H	Find and replace (edit mode)
Enter / Shift+Enter	Next / previous match
Esc	Close the find bar
Ctrl+B / Ctrl+I	Bold / italic (edit mode, toggles)
Ctrl+K	Insert link — the address part is pre-selected
Tab / Shift+Tab	Indent / outdent, multi-line aware
Ctrl+Tab / Ctrl+Shift+Tab	Next / previous tab
Ctrl+W	Close tab
Alt+← / Alt+→	Back / forward between documents
Ctrl+Wheel / Ctrl++ / Ctrl+-	Document zoom (remembered across runs)
Ctrl+0	Reset document zoom to 100%
Ctrl+/	View keyboard shortcuts

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Mermaid diagrams

Tag a fenced block mermaid and the bundled renderer displays it offline using the current theme. See the Mermaid documentation for supported syntax.

```mermaid
flowchart LR
    A["Draft"] --> B["Review"]
    B --> C["Publish"]
```

The fenced-block format is also understood by GitHub and GitLab. A syntax error is shown in that block without stopping the rest of the document from rendering.

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Privacy

• Your documents and settings never leave your machine. All rendering, editing, and exporting is local.
• During app use, network access is limited to the auto-update check: an anonymous GitHub Releases request and a release download only when you start an update. On first installation, Setup may also download Microsoft's WebView2 Runtime if Windows does not already have it. No document content, analytics, or identifiers are sent.
• The installed edition stores theme and language preferences, session recovery data, recent-document paths, and WebView2 cache under %LOCALAPPDATA%\MarkDownEditor. The portable edition stores them in WebView2Data/ beside the executable, with %TEMP%\MarkDownEditor as a read-only fallback.
• The preview removes executable content and does not load remote images automatically. Local images remain on your machine.

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Feedback

Bug reports and feature requests are welcome on GitHub Issues. You can also click the version label next to the title inside the app — the bug report form arrives pre-filled with your version.

License

MIT — see LICENSE. Bundled third-party components are listed in THIRD-PARTY-NOTICES.md.