Rule Number 9, LLC

Awesome Markdown

A fast, beautifully rendered Markdown viewer and live editor: the mdtool terminal app for macOS, Linux, and WSL, and a native SwiftUI macOS app — both built on one shared Rust core, mdcore.

v0.0.1 · MIT OR Apache-2.0 · no telemetry, no tracking

View on GitLab

mdtool directory workspace in a terminal: a file-tree sidebar listing the project's docs folder on the left, with USER_GUIDE.md open in a tab on the right, rendered with colored headings, links, and a syntax-highlighted quick-start block.
mdtool docs/ — the directory workspace browsing this project's own documentation: file tree, tabs, and a live-rendered preview.

What it does

Read

  • Terminal rendering with color theming and code syntax highlighting
  • Clickable links via OSC 8 terminal hyperlinks
  • Scrollable pager: / search, t heading outline, built-in help
  • Dark, light, and auto themes; selectable heading styles

Write

  • Split-pane live editor with scroll-synced preview
  • Find & replace, undo/redo
  • External file changes picked up automatically
  • Native macOS app with the same split-pane editing, via the shared Rust core

Organize

  • Directory workspaces with a file-tree sidebar
  • Tabbed documents, each keeping its own scroll position
  • Cross-document search

Install

Homebrew (macOS & Linux):

brew install --formula https://gitlab.com/rule-number-9/awesome-markdown/-/raw/master/Formula/awesome-md.rb

Cargo (any Rust toolchain) — installs the mdtool binary:

cargo install mdcli

Prebuilt binaries are attached to tagged releases, and the macOS app ships as a signed, notarized download there as well.

See it running

Everything below is a real capture of mdtool 0.0.1 running in a terminal — nothing is mocked up.

mdtool README.md — the interactive pager

mdtool pager rendering a Markdown document in a dark-themed terminal: highlighted headings, an ordered list, a blockquote, and green-checked task-list items, with a status bar showing the scroll position and key hints for search, outline, and help.
Themed rendering with a status bar: j/k scroll, / search, t outline, ? help.

Press t — jump anywhere from the heading outline

The same mdtool pager with the heading-outline overlay open: a bordered panel listing the document's five section headings, with the first entry selected and key hints to navigate, jump, or close.
The outline overlay lists every heading; Enter jumps straight to a section.

mdtool -e notes.md — the split-pane live editor

mdtool's split-pane editor: raw numbered Markdown source being edited on the left, the live-rendered preview on the right, and a status bar with key hints for save, find, open, replace, and undo.
Edit on the left, rendered preview on the right — panes stay scroll-synced while you type.

And it plays nicely with pipes

cat README.md | mdtool      # render to stdout
mdtool README.md | less -R  # one-shot render, paged by your own pager

Project & licensing

Awesome Markdown is open source under MIT OR Apache-2.0; the name, logo, and icons remain trademarks of Rule Number 9, LLC. It collects nothing: no telemetry, no analytics, no network calls, no tracking.

Questions and bug reports are welcome on the issue tracker. Please report security issues privately to contact@rulenumber9.net.