mdr — Markdown Reader

A lightweight, fast Markdown viewer with Mermaid diagram support and live reload. Built in Rust.

Why?

Developers working with LLMs constantly receive Markdown with code blocks, tables, and Mermaid diagrams. There's no simple mdr file.md command to view it all rendered properly.

• Not an editor — read-only viewer, opens instantly
• Not Electron — native Rust binary, no Node.js, no npm
• Mermaid built-in — diagrams render as SVG natively (no headless browser)
• Live reload — edit your file, see changes instantly

Backends

mdr offers multiple rendering backends, selectable at runtime:

Backend	Stack	Strengths
egui (default)	Pure Rust GPU rendering	Single static binary, fast startup, cross-platform
webview	OS native WebView (WebKit/WebView2)	GitHub-quality HTML/CSS rendering, full CSS support
tui	Terminal UI (ratatui + crossterm)	Works over SSH, no GUI needed, keyboard-driven

Install

From source

git clone https://github.com/CleverCloud/mdr.git
cd mdr
cargo install --path .

Build with specific backends only

# egui only (smaller binary, no WebView dependency)
cargo install --path . --no-default-features --features egui-backend

# webview only
cargo install --path . --no-default-features --features webview-backend

Usage

# Open with default backend (egui)
mdr README.md

# Open with webview backend
mdr --backend webview README.md

# Open in terminal (TUI)
mdr --backend tui README.md

# Show help
mdr --help

TUI keybindings

Key	Action
q / Esc	Quit
j / ↓	Scroll down
k / ↑	Scroll up
Space / PgDn	Page down
PgUp	Page up
g / Home	Go to top
G / End	Go to bottom
Tab	Switch focus between TOC and content
Enter	Navigate to selected TOC heading

Features

• Full GFM support — tables, task lists, strikethrough, footnotes, autolinks
• Syntax highlighting — code blocks with language detection (via syntect)
• Mermaid diagrams — flowcharts, sequence diagrams, pie charts, and more (via mermaid-rs-renderer)
• Table of Contents — auto-generated sidebar from headings with click-to-navigate
• Live reload — file watching with 300ms debounce, updates on save
• Dark/Light theme — follows OS theme (webview backend)

Mermaid Support

Mermaid code fences are rendered as SVG diagrams:

```mermaid
graph TD
    A[Input] --> B[Process]
    B --> C[Output]
```

Supported diagram types: flowchart, sequence, pie, class, state, ER, gantt.

Note: Diamond/decision nodes ({text}) are not yet supported by the underlying renderer. Use square brackets as a workaround.

Architecture

src/
├── main.rs              # CLI (clap), backend dispatch
├── core/
│   ├── markdown.rs      # GFM parsing (comrak) + CSS
│   ├── mermaid.rs       # Mermaid → SVG rendering
│   ├── toc.rs           # Heading extraction for TOC
│   └── watcher.rs       # File watching (notify, 300ms debounce)
└── backend/
    ├── egui.rs          # egui/eframe backend
    ├── tui.rs           # ratatui/crossterm TUI backend
    └── webview.rs       # wry/tao WebView backend

Building

Requires Rust 1.75+.

# All backends (default)
cargo build --release

# Run tests
cargo test

# Run clippy
cargo clippy

Linux dependencies

sudo apt-get install libgtk-3-dev libwebkit2gtk-4.1-dev libxdo-dev libgl1-mesa-dev

Releases

Pre-built binaries are available on the Releases page for: - macOS (Apple Silicon + Intel) - Linux (x86_64) - Windows (x86_64)

To create a release, push a version tag:

git tag v0.1.0
git push origin v0.1.0

License

MIT

Contributing

Issues and PRs welcome at github.com/CleverCloud/mdr.