showmd

What is showmd?

showmd is a free Quick Look extension for macOS that previews Markdown files (.md and related extensions) in a more readable way than Finder’s default behavior. Its core purpose is to render Markdown with formatting, while keeping access to the source content.

Instead of showing raw text when you press Space on a .md file in Finder, showmd renders Markdown and also provides a rendered/source toggle. It additionally parses YAML frontmatter into a collapsible metadata table, supporting common documentation and AI-prompt workflows that rely on Markdown structure.

Key Features

• Quick Look preview for Markdown in Finder: Press Space on a Markdown file to view formatted output without opening a browser or editor.
• Rendered ↔ source toggle: Switch between rendered Markdown and the raw Markdown source with a single click.
• YAML frontmatter as a collapsible metadata table: Detects “keys found” in frontmatter and shows it in a table collapsed by default.
• Markdown features via a Markdown parser: Supports GitHub Flavored Markdown elements such as tables, task lists, strikethrough, autolinks, footnotes, and more.
• Syntax-aware rendering for code and special content: Code blocks use language-aware highlighting (190+ languages listed), inline and block LaTeX math render via KaTeX, and Mermaid diagrams render from code blocks.
• AI-oriented tag rendering: Custom XML-like tags commonly found in AI prompts (for example, , , ) are rendered as labeled, bordered blocks instead of raw angle brackets.
• No cloud or background uploads described: The page states “No cloud. No uploads. No telemetry,” meaning files are previewed locally by default.
• Inline image handling in Quick Look: Relative image paths resolve correctly so local screenshots/diagrams can appear within the preview.

How to Use showmd

1. Download showmd for macOS and open it once.
2. In System Settings → Privacy & Security → Extensions → Quick Look, enable showmd (the page describes this as a single toggle).
3. In Finder, select a Markdown file and press Space to preview it with showmd.
4. Use the rendered/source toggle to switch between formatted output and the underlying Markdown. The page also notes an option to copy as HTML.

Use Cases

• Reading documentation stored as Markdown: Preview README files with formatted headings, lists, links, and tables, without leaving Finder.
• Inspecting AI prompt/config files written in Markdown: View AI-agent instruction files where the content includes XML-like tags, with tags rendered as labeled blocks for faster scanning.
• Reviewing YAML frontmatter in static site content: Expand the frontmatter table when you need to check titles or configuration keys, while keeping it collapsed during casual reading.
• Checking technical content that includes code, math, or diagrams: See syntax-highlighted code blocks, LaTeX expressions, and Mermaid flowcharts rendered inline rather than as raw text.
• Verifying relative images in local notes/repo docs: Confirm that images referenced by relative paths appear correctly in the Quick Look preview.

FAQ

How do I enable showmd in Finder? Download showmd, open it once, then go to System Settings → Privacy & Security → Extensions → Quick Look and enable the extension. On first launch, macOS may prompt for permission to access data from other apps; click Allow.

Does showmd replace the need to open a browser? The page frames showmd as a way to preview Markdown directly in macOS Quick Look, rather than needing to open a browser to see rendered output.

Can I switch between rendered output and the original Markdown? Yes. showmd provides a rendered & source toggle, described as a single click.

How does showmd handle YAML frontmatter? It parses YAML frontmatter into a collapsible table, collapsed by default, which you can expand to view metadata.

Is there a cloud component? The page states “No cloud. No uploads. No telemetry,” indicating previews are handled locally by default.

Alternatives

• Open Markdown files in a dedicated Markdown viewer/editor: Use an app designed for Markdown rendering and export. These options often include more editing tools, while showmd is positioned specifically as a Quick Look previewer.
• Use a browser-based Markdown renderer: Upload or paste content into an online viewer to get rendered output. Compared with showmd, this adds a browser step and may not keep files strictly local.
• Rely on the macOS Quick Look default: Finder’s Space preview will show raw Markdown source. This is simplest but less readable for formatted content like tables, diagrams, and math.
• Use a documentation/static site toolchain to preview content: Local dev servers can render Markdown with full site styling, but are typically heavier than a Quick Look preview workflow.