You've got a Markdown file and you just want to read it, not edit it, not export it, just read the thing. But double-clicking opens some editor, and pressing Space in Finder shows you raw markup. Here's every way to fix that on a Mac, cheapest first.
The terminal
For a quick look at a short file, cat README.md or less README.md does the job. You're reading raw markup, but Markdown was designed to be readable as plain text, so for a short file that's often enough.
For actual rendering in the terminal, use glow:
brew install glow
glow README.md
It renders the Markdown right there in the terminal, formatted, not raw. It's free, MIT-licensed, made by Charmbracelet, and if you live in a terminal it might be all you need.
VS Code
If VS Code is your editor, Markdown preview is built in, no extension required. Open the file and press Shift+Cmd+V for the preview, or Cmd+K then V to open it beside the source. For a developer who's in VS Code all day anyway, that covers most needs, and I say that as someone who sells a Markdown viewer.
The downside is that you're launching an IDE to read one file, and there's no Finder integration.
The browser
Online Markdown renderers work: paste your text, see it rendered. For a public README that's fine. Don't paste private documents into them, though. That text is going to someone's server.
There are also browser extensions that render local .md files in a tab once you grant them file access. Workable, but now you're maintaining browser permissions to avoid installing a viewer.
Stock Quick Look
Select a file in Finder, press Space. It's the right reflex: instant, built into macOS, works great on images, PDFs, and plain text. But out of the box it doesn't render Markdown: a .md file previews as plain, unstyled text, markup and all.
Quick Look is extensible, though. Two apps fix it.
Quick Look with an extension
QLMarkdown is free and open source (GPL-3.0), actively maintained (1.5.2 shipped June 2026), and renders through cmark-gfm, GitHub's own fork of the reference parser. Install it from Homebrew or GitHub, launch it once so macOS discovers the extension, enable it in System Settings, and Space-bar previews are solved for $0.
Peekdown is my app, $3.99 on the Mac App Store. The extension enables automatically on install, renders GitHub-style with tables, task lists, and syntax highlighting, and handles Obsidian syntax (callouts, wikilinks, highlights, tags) and .mdx files. It's also a full viewer, so double-clicking a Markdown file opens a reading window instead of an editor. It needs macOS 15.0 or later.
If Space-bar previews are all you want, QLMarkdown gets you there free. Peekdown covers the double-click too.
Dedicated viewers
If you want to compare everything in this category — previewers like Marked 2, writing environments like Typora, the free options, what's maintained and what isn't — I wrote a full roundup: Best Markdown Viewers for Mac (2026).
What I use
Peekdown as the default app and the Quick Look extension, no surprise there, and glow when I'm already in a terminal. Between those two, I haven't had to open an editor just to read a Markdown file in a long time.