Ever asked yourself why all of those SKILL.md files are rendered in plain text in MacOS Preview? showmd is a free, native macOS Quick Look extension that renders Markdown beautifully. YAML frontmatter parsed into a collapsible metadata table — collapsed by default, one click to expand. No other viewer does this. Agentic AI XML tags — , , , and 17 more — rendered as labeled, bordered blocks instead of raw angle brackets.