I press spacebar on a .md file and nothing happens (or it shows raw text). What's wrong?

The Quick Look extension needs to be enabled. Open System Settings → General → Login Items & Extensions, scroll to Quick Look, click ⓘ, and switch Readdown on. Then relaunch Readdown to reset the Quick Look cache.

Spacebar preview stopped working after I uninstalled another markdown app. How do I fix it?

macOS needs to re-discover which extension handles markdown files. Quit and reopen Readdown — it automatically refreshes the Quick Look registry on launch. If that doesn't help, restart your Mac. Still stuck? Re-enable the extension manually: System Settings → General → Login Items & Extensions → Quick Look → ⓘ, then toggle Readdown off and back on.

Which file types can Readdown open?

.md, .markdown, .mdown, and .mkd. All standard Markdown extensions. UTF-8, UTF-16, and Latin-1 encodings are detected automatically.

How does syntax highlighting work?

Code blocks with a language name on the opening fence (e.g. python, swift, json) are highlighted using that language. Blocks without a language are auto-detected from 19 common languages. For best results, always specify the language.

Does Readdown support Mermaid diagrams?

Yes. Use mermaid as the language on a fenced code block and it renders as a diagram. Flowcharts, sequence diagrams, pie charts, and more. Works fully offline.

Can I edit files in Readdown?

No. Readdown is read-only by design. It never modifies your files. Use your favorite editor to write, Readdown to read.

How do I search within a document?

Press ⌘F (or Edit → Find…) to open the find bar. ⌘G jumps to the next match, ⇧⌘G to the previous, Esc closes it. The match counter shows your position ("3 of 17").

How do I make Readdown my default markdown app?

Readdown asks on first launch. You can also right-click any .md file in Finder → Get Info → Open With → select Readdown → Change All.

I clicked "Set as Default" but .md files still open in another app. What do I do?

Update macOS to 26.4+ or set Readdown as default manually: right-click any .md file in Finder → Get Info → Open With → Readdown → Change All.

Does Readdown update automatically?

Yes. Readdown checks for updates in the background via Sparkle. You can also check manually from Readdown → Check for Updates.

How do I report a bug or request a feature?

Open an issue on GitHub, or use Help → Send Feedback in the app.

ReaddownMarkdown reader & Quick Look preview for Mac

Stop opening .md files in Xcode, VS Code, or whatever your Mac defaults to. Double-click to read, spacebar to preview. Nothing more.

Download for Mac

Requires macOS 13 Ventura or later

Does one thing well.

Double-click to read

Opens .md files as rendered documents. Read-only by design. No edits, no auto-formatting, your files stay untouched.
Spacebar to preview

Quick Look extension for Finder. Select any .md, press spacebar. Rendered markdown, not raw text.

Native fonts
Syntax highlighting
Mermaid diagrams
Dark mode
Live refresh
Find in document
Adjustable zoom
Print & PDF export
Auto-updates

“Let’s be real, with Claude it’s Markdown all day long… and Readdown is hands down the best Markdown in town! I am always exploring docs, code snippets, mermaid diagrams, and it has everything blazing fast and beautiful.”

Rafael Bandeira @rafb43

Setup

Get started in three clicks.

Install and open any .md file

Drag Readdown to Applications. On first launch, it offers to become your default Markdown reader.
Enable Quick Look

Readdown prompts you to enable Quick Look so you can preview .md files with spacebar in Finder. Click Open Extensions Settings to jump straight to Login Items & Extensions, then click ℹ︎ next to Quick Look.
Toggle Readdown on

Switch Readdown on and click Done. Select any .md in Finder, press spacebar. Rendered.

Common Questions

I press spacebar on a .md file and nothing happens (or it shows raw text). What's wrong?

The Quick Look extension needs to be enabled. Open System Settings → General → Login Items & Extensions, scroll to Quick Look, click ℹ︎, and switch Readdown on. Then relaunch Readdown to reset the Quick Look cache. See the setup steps above for screenshots.
Spacebar preview stopped working after I uninstalled another markdown app. How do I fix it?

macOS needs to re-discover which extension handles markdown files. Quit and reopen Readdown. It automatically refreshes the Quick Look registry on launch. If that doesn't help, restart your Mac. Still stuck? Re-enable the extension manually: System Settings → General → Login Items & Extensions → Quick Look → ℹ︎, then toggle Readdown off and back on.
Which file types can Readdown open?

.md .markdown .mdown .mkd. All standard Markdown extensions. UTF-8, UTF-16, and Latin-1 encodings are detected automatically.
How does syntax highlighting work?

Code blocks with a language name on the opening fence (e.g. python, swift, json) are highlighted using that language. Blocks without a language are auto-detected from 19 common languages. For best results, always specify the language.
Does Readdown support Mermaid diagrams?

Yes. Use mermaid as the language on a fenced code block and it renders as a diagram. Flowcharts, sequence diagrams, pie charts, and more. Works fully offline.
Can I edit files in Readdown?

No. Readdown is read-only by design. It never modifies your files. Use your favorite editor to write, Readdown to read.
How do I search within a document?

Press ⌘F (or Edit → Find…) to open the find bar. ⌘G jumps to the next match, ⇧⌘G to the previous, Esc closes it. The match counter shows your position (“3 of 17”).
How do I make Readdown my default markdown app?

Readdown asks on first launch. You can also right-click any .md file in Finder → Get Info → Open With → select Readdown → Change All.
I clicked "Set as Default" but .md files still open in another app. What do I do?

Update macOS to 26.4+ or set Readdown as default manually: right-click any .md file in Finder → Get Info → Open With → Readdown → Change All.
Does Readdown update automatically?

Yes. Readdown checks for updates in the background via Sparkle. You can also check manually from Readdown → Check for Updates.
How do I report a bug or request a feature?

Open an issue on GitHub, or use Help → Send Feedback in the app.

What's new

1.14.1 June 2026
- Heading anchor links now match GitHub's slug convention for headings with stripped punctuation (e.g. # Foo — bar produces foo--bar, not foo-bar) — thanks @ReubenCowell
1.14 June 2026
- Paragraph lines beginning with # followed by a digit no longer freeze the app
- Fenced code blocks inside list items render as code blocks again
- Heading anchor links scroll to the target instead of being silently cancelled
- Underscores inside words (snake_case, lots_of_underscores) stay literal
- Mermaid diagrams in dark mode are legible again
- Readdown no longer hangs at launch when the previous session's documents have moved or been deleted
1.13 June 2026
- Code spans render exactly as written — underscores, asterisks, and HTML tags inside backticks stay literal
- Nested bullet lists render correctly
- Markdown files saved with a UTF-8 byte-order mark open cleanly
- Refined task-list checkboxes
- Mermaid diagrams use a refreshed theme that reads well in light and dark mode
1.12 May 2026
- Refreshed typography — warmer text, a cleaner heading scale, and restyled links and tables
- Linkable headings — every heading gets an anchor, so in-page #section links jump and scroll
- Quick Look previews no longer hang on a loading spinner on some recent macOS builds
- Open documents now reliably reappear after an update or relaunch
1.11 May 2026
- Live refresh — documents update automatically when edited in another app
- Refreshed window chrome on macOS Tahoe — larger rounded corners, cleaner title bar
- Thin auto-hiding scrollbar
- Redesigned find bar
- Open documents reopen automatically after relaunch (Sparkle update, login, force-quit)
- Pinch-to-zoom now matches Cmd-scroll range (50%–300%) instead of stopping at 100%
1.10 April 2026
- Fluid layout — documents reflow as you resize the window
- Window cascading when you open multiple files
- Zoom in / out / reset (Cmd +, Cmd -, Cmd 0), pinch and Cmd-scroll to zoom
- Find in document (Cmd+F) with live match counter
- Autolinks, HTML entities, and URLs with parens now render correctly
- Soft line breaks reflow naturally — no more source-width wrapping
- "Set as Default" prompts automatically on first launch
- PDF and print output preserves syntax highlighting, rules, and checkbox fills
1.9.3 April 2026
- Security hardening for HTML content in markdown files
- Smaller, more readable font in Quick Look previews
- Cleaner code block styling to match GitHub
1.9.2 April 2026
- Fix auto-update failing on some systems — if "Check for Updates" gave you an error, re-download here and future updates will work
1.9.1 April 2026
- Fix PDF export from the print dialog (Save as PDF, Open in Preview)
- Add Export as PDF (Cmd+Shift+E) with continuous or paginated layout
- Print-friendly styling for cleaner output
1.9 March 2026
- Mermaid diagram support, fully offline
- Print support with Cmd+P
1.8.2 March 2026
- Auto-detect syntax highlighting for code blocks without a language tag
- Set as Default now covers .md, .markdown, .mdown, and .mkd
1.8.1 March 2026
- Fix runaway memory usage from highlight.js auto-detection
- Cache rendered HTML, pre-compile regex patterns
- Tilde fence support
1.8 March 2026
- Syntax highlighting for fenced code blocks
- Automatic updates via Sparkle

Older releases

1.6 March 2026
- Welcome screen with Quick Look setup guide
- Better list rendering
1.5 March 2026
- Fixed launch crash
- Added public.markdown UTI support
1.4 March 2026
- HTML passthrough
- Multi-encoding support (UTF-16, Windows-1252, Latin-1)
- URL safety improvements
- Base URL support for relative paths
1.3 March 2026
- Fix Quick Look extension for macOS 15
1.2 March 2026
- Improved first-launch experience
- Fixed Settings deep link for Extensions pane
1.1 February 2026
- Welcome sheet on first launch
- Quick Look preview extension
- Styled DMG installer
1.0 February 2026
- Initial release

ReaddownMarkdown reader & Quick Look preview for Mac

Does one thing well.

Double-click to read

Spacebar to preview