Quick Look Markdown on Mac after macOS 27.3
On 3 November 2026, 9to5Mac reported that macOS 27.3 beta 1 renders .md files in Quick Look instead of showing the raw syntax. MacRumors described the same change the next day: select a file in Finder, press Space, and the preview shows styled headings, bold text, lists, and links, without a separate editor or a Quick Look extension.
That is a real improvement for a short note. It does not, on its own, replace every Markdown preview on the Mac.
What the reports actually describe
Both reports are about the 27.3 update, starting with the beta Apple released on 3 November 2026. They name four things the preview styles: headings, bold text, lists, and links. They also connect the change to Apple's wider use of Markdown, including Notes and the SKILL.md files in the new Siri app-skills work.
They do not describe tables, task lists, Mermaid diagrams, colored code blocks, or .mdx files. A short README of headings and bullets may be enough once that Mac is on 27.3. A spec with a table, a diagram, or MDX is a different file, and the reports do not say Quick Look draws those.
A Mac that is not on 27.3 still shows the old preview. Space on README.md is a text dump. The hash marks, the asterisks, and the table pipes stay on screen. The 27.3 preview is part of that update. It is not a switch you can flip in System Settings on an older system.
When a Quick Look extension still helps
A Quick Look extension is a small app that registers a preview. You open the app once, then enable it under System Settings, General, Login Items & Extensions, Quick Look. macOS uses one renderer for a file type. Glance, on its QLMarkdown comparison page, says that leaving two Markdown extensions enabled makes the result a coin toss. Turn the others off.
Three honest choices this week:
Stay with the system preview once the Mac is on macOS 27.3 and the files are simple. There is nothing to install. You give up whatever those reports did not show.
QLMarkdown, the open-source extension from sbarex, is free. The Homebrew cask lists version 1.5.7. The project is a preview, not an editor, and its own page says it can render Mermaid, math, and syntax highlighting when those options are on. You install it yourself, outside the Mac App Store.
Glance prices reading as free and editing the rendered page as a one-time $9.99, on the comparison page above. That page is selling Glance. The useful distinction is the split: a preview and an editor are different jobs.
What MD Quick Preview does
MD Quick Preview is a free Mac app from PatakoLabs. It is a Quick Look extension. It is not an editor, and it is not a notes app. Press Space on .md, .markdown, .mdown, .mkd, or .mdx and the preview is GitHub-style HTML, in light or dark, drawn on the Mac with cmark-gfm. The file is not uploaded.
The preview includes tables, strikethrough, task lists, Mermaid diagrams, and syntax highlighting. MDX keeps the prose and the fenced code. It drops front matter, imports, exports, and JSX wrappers, so a component file will not look like the running page.
It runs on macOS 13 or later. It is free on the Mac App Store. A Developer ID-signed zip is on the same page if you would rather install outside the store: download the zip. There is no account and no paid tier. The free app is the whole preview.
Finder keeps the keyboard, so Find from a Quick Look preview opens the file in MD Quick Preview and focuses the find bar. Inside that window, Command-F searches the preview.
What it leaves out
MD Quick Preview does not replace the system preview for someone who only needs headings and lists on macOS 27.3 and does not want another extension. It does not edit the file. It does not render JSX, and it does not run code the way a notebook would. If two Markdown extensions are enabled, macOS does not promise which one answers. Disable the other one.
If you already write in an editor that previews Markdown, you do not need a Finder extension for the writing itself. Quick Look is the glance from Finder, before the file is opened.
The older page is still the right one for the install-path choice against QLMarkdown: MD Quick Preview vs QLMarkdown.
Turn the extension on
- Install MD Quick Preview from the Mac App Store, or open the signed zip and move the app to Applications.
- Launch the app once, so macOS registers the extension.
- Open System Settings, then General, then Login Items & Extensions, then Quick Look.
- Enable MD Quick Preview, and turn off any other Markdown preview in that list.
- In Finder, select a
.mdfile and press Space.
If the preview is still plain text, the extension is off, another extension won, or the app has not been launched yet. Launch it again and check that list. There is no cloud account to sign into.
The short version
macOS 27.3, as reported on 3 and 4 November 2026, puts basic Markdown into Quick Look. That helps a simple file on a Mac that has the update. The reports do not describe tables, diagrams, or MDX, and Finder on an earlier system is unchanged.
MD Quick Preview is the free, on-device option for those files. Install it from the Mac App Store or the signed zip, turn the extension on, and leave the other Markdown previews off.