Mud: Mark Up or Down

Markdown is suddenly everywhere. It’s how we speak to machines now. It’s how they speak to us. We should make it nice! But you already have a favorite text editor. You don’t need a special tool for writing Markdown. You just need a way to preview the Markdown you’re writing, marked up. That’s what Mud is for. It renders Markdown beautifully, bright or dark. It automatically reloads the document when you save it — or when Claude Code writes to it, or Codex, or whatever you use. Mud shows you both sides of every document: - Mark Up renders your Markdown as styled HTML — GitHub-flavored, with syntax-highlighted code. - Mark Down shows the raw source with line numbers. Hit Space to flip between them. Your scroll position carries over. Mud is a Mac-gassed Mac app with excellent command-line tooling. It’s free and it’s open source. It does one thing — it marks up Markdown! — and it does it really well.