Marker documentation

How it's built

Marker is a single SvelteKit frontend (static/SPA build) that runs unmodified in two hosts. A platform-detection layer decides at runtime how files actually get read and written: through Tauri's Rust backend on desktop, or through the browser's File System Access API on the web. The editor pane is CodeMirror 6, lazy-loaded so it costs nothing until you open Edit or Split. Rendering goes through marked with marked-highlight and highlight.js for syntax-highlighted code fences, and every rendered file is passed through DOMPurify.sanitize() before it reaches the page — there's no "trusted source" exception, since the whole point is opening files from disk.

View, Edit and Split modes

Every open file has a mode: View renders the markdown read-only, Edit shows the CodeMirror source editor, and Split shows both side by side, live. Ctrl/Cmd+E toggles between View and Edit; Split is a separate toolbar option. Switching modes never discards unsaved changes — the underlying content is the same string regardless of which pane is showing it.

Opening files and folders

Open File opens a single .md file. Open Folder lists that folder's top-level markdown files in the sidebar so you can switch between them with a click — it does not recurse into subfolders. Selecting a different file while the current one has unsaved changes triggers a confirmation prompt before switching.

Saving

Ctrl/Cmd+S saves the current file in place. On desktop this writes directly to the original path via a Tauri command, with a retry if the write is momentarily blocked (e.g. by another process holding the file). In the browser, save-in-place works the same way in Chromium browsers via the File System Access API; in browsers without that API, saving downloads a new file instead of overwriting the original.

Keyboard shortcuts

Installation

Windows

Download Marker_<version>_x64-setup.exe or the .msi from the latest release and run it — either installer works. Marker isn't code-signed, so Windows SmartScreen will show an "unrecognized publisher" warning the first time: click More info, then Run anyway.

macOS

Download the .dmg matching your Mac's chip: _aarch64.dmg for Apple Silicon, _x64.dmg for Intel. The app isn't code-signed, so Gatekeeper blocks the first launch — right-click the app in Applications and choose Open once to bypass it. (The .app.tar.gz files in each release are auto-update artifacts, not for manual download.)

Linux

Use whichever package matches your distro: .deb for Debian/Ubuntu, .rpm for Fedora/RHEL, or the .AppImage for any distro (make it executable and run it directly).

Browser (no install)

Open markdw.netlify.app. In Chrome or Edge, folder browsing and save-in-place work via the File System Access API, matching the desktop experience. In Firefox, Safari and other browsers without that API, you can still open and edit a single file, but saving downloads a new copy instead of overwriting the original.

Troubleshooting

Windows blocks the installer with a SmartScreen warning

This is expected for an unsigned build. Click "More info" in the SmartScreen dialog, then "Run anyway."

macOS says the app is damaged or can't be opened

Right-click (not double-click) the app in Finder and choose Open — this is Gatekeeper's one-time confirmation for unsigned apps, not an actual problem with the download.

Save isn't overwriting my file in the browser

Save-in-place needs the File System Access API, which only Chromium-based browsers (Chrome, Edge) currently support. In other browsers, saving always downloads a new file — this is a platform limitation, not something the app can work around.

A subfolder's markdown files aren't showing up

Open Folder only lists a folder's top-level .md files by design; it doesn't recurse into subfolders. Open a subfolder directly, or open the file individually with Open File.

Source & license

Marker is MIT-licensed and open source. Full source, issues and releases are on GitHub.