rumd

A cross-platform markdown viewer in pure Rust. View a file rendered or as syntax-highlighted source, and it refreshes automatically when the file changes on disk.

Features

• Rendered markdown: GFM tables, task lists, strikethrough, syntax highlighted code blocks, clickable links, local images (relative paths resolve against the document's directory)
• Centered reading column with adjusted typography
• Collapsible table of contents (Ctrl/Cmd+T): a resizable sidebar on the left lists every heading; groups expand/collapse, and clicking an entry jumps the rendered view to that heading (or moves the source caret in Source view)
• Split view: rendered and source side by side
• Editing: the source pane is always editable (Source and Split views) and the rendered view updates live as you type, following the edited section; save with Ctrl/Cmd+S. Unsaved changes show a • in the window title
• If the file changes on disk while you have unsaved edits, a banner lets you keep editing or reload from disk — your edits are never overwritten
• Files that are not valid UTF-8 stay read-only (saving is disabled to avoid corrupting them)
• Search (Ctrl/Cmd+F): every visible occurrence is highlighted in both views — the current match in yellow with black text, the others with a subtle wash (Enter/Shift+Enter steps through matches)
• Source view: line numbers, markdown highlighting
• Dark/light theme, follows the system theme by default
• Zoom (Ctrl/Cmd+=, Ctrl/Cmd+-, Ctrl/Cmd+0, Ctrl/Cmd+scroll)
• Auto-reload on file changes (degrades to manual refresh if the OS watch limit is hit)
• Theme, zoom, view mode, and ToC visibility persist between runs
• Open via drag-and-drop, file dialog, or command line: rumd README.md

Shortcuts

Shortcut	Action
Ctrl/Cmd+O	Open file
Ctrl/Cmd+S	Save edits
Ctrl/Cmd+E	Cycle rendered/split/source
Ctrl/Cmd+T	Toggle the table of contents
Ctrl/Cmd+D	Toggle dark/light theme
Ctrl/Cmd+F	Search
Enter / Shift+Enter	Next / previous match
Esc	Close search
Ctrl/Cmd+= / Ctrl/Cmd+- / Ctrl/Cmd+0	Zoom in / out / reset
Ctrl/Cmd+scroll / pinch	Zoom in / out
F5	Reload from disk (asks first if there are unsaved edits)

Building

Requires a recent stable Rust toolchain (1.95 or newer).

• Linux: X11/Wayland development libraries are needed at build time, e.g. on Debian/Ubuntu: sudo apt install libxkbcommon-dev libwayland-dev libx11-dev
• macOS: no extra prerequisites
• Windows: no extra prerequisites

cargo build --release

The binary is at target/release/rumd.

Flatpak

Build and install from source as a system-wide Flatpak (flatpak-builder and the org.freedesktop.Platform//26.08 runtime, SDK, and rust-stable extension are required):

flatpak install --system flathub \
  org.freedesktop.Platform//26.08 org.freedesktop.Sdk//26.08 \
  org.freedesktop.Sdk.Extension.rust-stable//26.08
flatpak-builder --install --system --force-clean build flatpak/io.github.dkijkuit.rumd.yml
flatpak run io.github.dkijkuit.rumd

Release checklist

1. Bump the version in Cargo.toml and commit.
2. Update the Features and Shortcuts sections here if anything changed.
3. Mirror those changes on the website (website/index.html) — prose only: the version, download links, and screenshots are updated automatically on tag push.
4. Tag and push the tag: git tag vX.Y.Z && git push origin vX.Y.Z

The release workflow then builds the binaries, publishes the release, captures fresh website screenshots from tests/fixtures/sample.md with RUMD_CAPTURE=1 cargo test capture_website_screenshots, stamps the tag into the website, and deploys it to GitHub Pages.

Testing

cargo test

Headless UI tests run on all platforms without a display server.