QLMarkdown

QLMarkdown by sbarex is a free, open-source macOS application that installs a Quick Look extension for formatted Markdown previews. It suits developers, technical writers and users who want to inspect documentation in Finder without opening a full editor. This Homebrew package is the sbarex project, distinct from older projects with similar names.

Capabilities

• Preview Markdown through macOS Quick Look using cmark-gfm-based rendering.
• Configure light/dark themes, fonts, source rendering and preview options.
• Enable tables, task lists, footnotes, heading anchors and other extensions.
• Highlight fenced code and optionally render MathJax formulas or Mermaid diagrams.
• Preview supported R Markdown, Quarto, MDX, API Blueprint and textbundle files.
• Convert Markdown to HTML using the included command-line tool or experimental Shortcuts actions.

Installation and enabling the extension

Install with brew install --cask qlmarkdown, or unpack the official QLMarkdown.zip and place QLMarkdown.app in Applications. Launch the application at least once so macOS can discover the extension and the app can prepare shared support files. In the main app, use the button that opens the Quick Look settings panel and check that the extension is enabled. On current macOS versions the documented path is System Settings > General > Login Items & Extensions > Quick Look; older systems arrange extension settings differently.

Select a supported Markdown file in Finder and press Space to preview it. In the configuration app, save settings with Command-S or File > Save settings, or enable autosave. The inline test editor exists to check formatting; the developer does not present the app as a standalone Markdown editor or general document viewer. R Markdown preview does not execute R code, and MDX preview does not render JSX.

If another app also registers Markdown Quick Look support, its extension or file-type registration may take precedence. The official troubleshooting guide recommends testing other Quick Look extensions individually to identify conflicts. The cask itself declares no explicit conflicting cask or additional formula dependency. Homebrew also links the included qlmarkdown_cli tool; it uses its own settings rather than sharing the app's Quick Look configuration.

Requirements, permissions and platform limits

The current Homebrew cask requires macOS 12 Monterey or later and lists Intel and Apple Silicon support. This is a macOS Quick Look application; no official Windows or Linux client for this project was established. The precompiled release is described upstream as signed and notarized. Building from source has development dependencies, but those are not additional installation requirements for the packaged app.

The Quick Look extension uses a read-only permission exception to resolve local preview images; this is not a general requirement to grant Accessibility or Full Disk Access. Local-image embedding and raw HTML are separate rendering options. Raw HTML can permit unsafe content, while the default strips HTML tags and unsafe links; review the upstream settings before enabling it for untrusted documents. MathJax and Mermaid can use network-hosted libraries or embed bundled code, so CDN mode requires internet access. Other remote resources also depend on network availability.

Accounts, cost and license

The app is free, open-source software with a GNU GPL version 3 license file. No account or subscription is required for local previews or HTML conversion; donations are optional. The official 1.5.7 ZIP is 26,322,745 bytes, a transfer size rather than installed space. No universal RAM or installed-space minimum was established.

The screenshot is the official tagged README example of a Mac Quick Look preview. It illustrates rendered Markdown and is not a freshly captured 1.5.7 installation.

Sources: Official tagged README and troubleshooting, Official 1.5.7 release, License, Homebrew cask.