Marked QL vs MDViewer
QuickLook extension vs full Markdown viewer — different scope, different purpose
Quick Overview
Marked QL is a QuickLook preview extension by Brett Terpstra, available on the Mac App Store for $9.99. It does one thing: when you press Space on a .md file in Finder, it renders the Markdown as formatted HTML instead of showing raw text. It supports math, diagrams, and syntax highlighting inside the QuickLook panel. It is not a standalone app — there is no window, no tabs, no file browser.
MDViewer is a full Markdown viewing app that also includes a QuickLook extension. You get the same Finder preview capability plus a persistent reading window with tabs, scroll-tracking table of contents, Git history, inline editing, and PDF export.
The core question is simple: do you only need QuickLook, or do you need a full viewer?
Feature Comparison
| MDViewer | Marked QL | |
|---|---|---|
| Price | Lite: Free / Pro: $9.99 | $9.99 (one-time) |
| What it is | Full app + QuickLook extension | QuickLook extension only |
| macOS requirement | macOS 13.0+ | macOS 13.0+ |
| Distribution | Direct download (DMG) | Mac App Store |
| App size | ~15 MB | ~3.9 MB |
| Standalone reading window | Yes | No |
| Finder QuickLook | Yes | Yes (primary feature) |
| Tabs | Yes | No |
| Table of contents | Yes (auto, tracks scroll) | No |
| Inline editing | Yes (double-click to edit) | No |
| Git history & diff | Yes (built-in) | No |
| PDF export | Yes (⌘⇧E) | No |
| Mermaid diagrams | Yes (interactive SVG with zoom) | Yes |
| Math (LaTeX/KaTeX) | Yes | Yes |
| Syntax highlighting | Yes | Yes |
| Live reload | Yes | No (preview closes on click) |
| File tree | Yes | No |
| GitHub Flavored Markdown | Yes | Yes |
When to Choose MDViewer
- You want QuickLook and a full reading app in one install
- You read Markdown files for more than a quick glance — you need to scroll, navigate, and reference sections
- You want a table of contents for long documents
- You need Git history and diffs for documentation files
- You want to make quick edits without opening a separate editor
- You need to export Markdown to PDF
- You want tabs to keep multiple files open
- You want a free tier that already includes QuickLook
When to Choose Marked QL
- You only need QuickLook preview in Finder — press Space, glance at the file, move on
- You already use Marked (the full app) for reading and editing, and want the matching QuickLook extension
- You prefer Mac App Store distribution with automatic updates
- You want the smallest possible install (~3.9 MB) with no app window to manage
QuickLook Extension vs Full App
QuickLook is a macOS feature that shows a preview when you press Space on a file in Finder. By default, macOS shows raw Markdown source — just plain text. Both Marked QL and MDViewer add extensions that render the Markdown as formatted HTML in that preview panel.
The difference is what happens next. With Marked QL, the QuickLook panel is all you get. You see the rendered preview, and when you press Space again or click elsewhere, it closes. If you need to spend time reading the document, navigate between sections, or cross-reference it with other files, you need a separate app.
With MDViewer, the QuickLook preview is just the entry point. If a quick glance is enough, press Space, look, done. If you need more, double-click the file and it opens in MDViewer’s full reading window — with a table of contents, tabs, scrolling, and everything else. One app handles both the quick preview and the deep-reading use case.
The Marked Ecosystem
Marked QL is part of Brett Terpstra’s Markdown tool ecosystem. The full Marked app is a separate, more expensive application that provides advanced Markdown rendering, proofing, and export. Marked QL serves as a lightweight companion that adds QuickLook to Finder without requiring the full app.
If you already own Marked and want consistent rendering in QuickLook, Marked QL is a natural addition. If you do not use Marked, paying $9.99 for a QuickLook-only extension is harder to justify when MDViewer Lite gives you both QuickLook and a full reading app for free.
For a comparison with the full Marked app, see MDViewer vs Marked 2.
FAQ
Is Marked QL a standalone Markdown viewer?
No. Marked QL is a QuickLook extension only. It renders Markdown when you press Space on a file in Finder, but it does not open a persistent reading window. For a full viewer, you need a separate app like MDViewer or Marked (the full app by the same developer).
Does MDViewer also have QuickLook support?
Yes. MDViewer includes a QuickLook extension that renders Markdown in Finder previews, plus it is a full reading app with tabs, table of contents, Git history, and inline editing. You get QuickLook and a standalone viewer in one app.
Can I use Marked QL and MDViewer together?
Technically yes, but only one QuickLook extension handles .md files at a time. macOS picks one based on priority. Since MDViewer already includes QuickLook, installing both means one extension goes unused. If you use Marked (the full app) for editing and MDViewer for reading, the QuickLook behavior depends on which app macOS prioritizes.
Try MDViewer
MDViewer Lite is free and includes QuickLook. Pro adds editing, Git history, and PDF export for $9.99. Download and get both QuickLook and a full viewer in one app.
Requires macOS 13.0 or later. Intel and Apple Silicon.