A tool to generate Markdown file QuickLook previews for macOS Big Sur and above

Latest Release: 2.3.0

 New Version

 

How to Use PreviewMarkdown

Install the app and run it. This will register the availability of the app’s QuickLook extensions, Markdown Previewer and Markdown Thumbnailer. You can now quit the app.

Using QuickLook in Finder — select a Markdown file (.md, .mdown or .markdown, for example) and press space — will pop up a rendered image of file:

PreviewMarkdown will optionally preview YAML front matter at the start of your Markdown files. YAML is often used this way to hold metadata that will be read by static website generators when they read the Markdown content for page rendering.

You can disable or re-enable Markdown Previewer and Markdown Thumbnailer in System Preferences > General > Login Items & Extensions.

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Customize the Preview

Click on the settings button , or select Settings… from the PreviewMarkdown menu, to switch to the settings tab to adjust some of the key elements of the preview:

  • The base text size, from 10pt to 28pt.
  • The primary text font and style.
  • Code blocks’ monospace font and style.
  • The line-spacing.
  • The colour of headlines.
  • The colour of code blocks.
  • The colour of blockquotes.
  • The colour of links.
  • The colour of YAML front matter field names (keys).
  • Whether YAML front matter should be included in previews.
  • Whether a whitespace border should be placed around the preview.
  • Whether previews should be displayed dark-on-light even in macOS Dark Mode.

Choose your preferred text size — headings are scaled up from this value in even steps — using the slider, then pick the fonts in which you want text and code to be presented. You can also choose each font’s style:

Choose your preferred heading, code, blockquote, link and YAML front matter field name colours by selecting the appropriate formatting element from the pop-up and then clicking on the colour well to bring up macOS’ standard colour picker. As you make your colour selection, the colour well will be updated. Switch to other formatting elements as you need, changing their colours as you go:

Click Apply to record your choices.

Changing these settings will affect all new previews immediately, though not any that are already open. Changes may not be seen in thumbnails until you open a folder that has not been previously opened during the current login session. Thumbnails are always presented dark-on-light, even under macOS’ Dark Mode. This is a Finder convention.

If you’ve made a bunch of changes and you don’t like the look of them, you may click the Defaults button to restore PreviewMarkdown’s standard settings. Don’t forget top click Apply to enforce the change — or just quit the app to keep the settings you applied before.

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Feedback and Bug Reports

You can use the in-app UI to submit feedback or contact me. Just click the feedback button , or select Report a Bug… from the Help menu, to switch to the feedback tab. Enter your message of up to 512 characters and click Send:

Please include your email address if you would like a response — I can’t respond without one. Please see the privacy policy for details of email address usage.

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Images

PreviewMarkdown 2 will include image placeholders when it encounters image links in Markdown files, along with the image file’s path. Unfortunately, macOS’ sandbox permissions system does not appear to allow the previewer access to arbitrary files, only to the previewed file itself. We are actively exploring solutions to this problem and hope to provide full image previews shortly.

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Troubleshooting

If it appears that either Markdown Previewer or Markdown Thumbnailer are not working after you have run the host app, please log out of your Mac and then log back in. You may also need to re-run the app after updating it.

Go to System Settings > General > Login Items & Extensions and click on the ⓘ symbol alongside the Quick Look entry under Extensions. Make sure Markdown Previewer and Markdown Thumbnailer are both switched on (see screenshot above)).

Some applications which can edit Markdown files may register a non-standard, proprietary Uniform Type Identifier (UTI) for Markdown files. PreviewMarkdown may not be aware of these UTIs and therefore may not be able to preview and thumbnail these files on your system. Finder will request previews and thumbnails not from PreviewMarkdown but from the app that ‘owns’ the Markdown UTI on your system.

PreviewMarkdown cannot display Markdown files if a pre-existing application has already taken ownership of the format. This is a limitation of macOS.

If you encounter this issue — typically, previews of markdown files will show the raw formatting text — please run utitool to see your system’s registered Markdown file UTI. This UTI will automatically be included in any message you send using PreviewMarkdown’s feedback facility.

Please include an email address in any feedback you provide or support request you make. I cannot respond to you without one.

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Enjoyed Using PreviewMarkdown?

If you have found PreviewMarkdown to be useful, please consider writing a positive review on the Mac App Store, or simply give it a rating.

Thank you!

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Acknowledgements

PreviewMarkdown makes use of code from the following sources:

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Source Code

You can view PreviewMarkdown’s source code at GitHub.

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Release Notes

  • 2.3.0 12 December 2025
    • Add extra setting to control preview window size: small (42% of main screen; standard QuickLook size), medium (50% of main screen) or large (75% of main screen)
    • Add extra setting for the preview whitespace margin. Default: 16.0 points (previous, locked value).
    • Add extra setting to match thumbnails to Finder display mode under macOS 26.1+. Default: preserve PreviewMarkdown behaviour.
    • New more intuitive graphic for unchecked checkboxes.
    • Fix front matter detection when horizontal rules are also included in the Markdown.
    • Fix inadvertent changes to the case of image URLs.
  • 2.2.4 11 November 2025
    • Fix for macOS 26.1 deciding thumbnails should match mode.
    • Correct light mode background colour.
    • Correct the link to help content.
  • 2.2.3 4 November 2025
    • Improve light-mode colouring for code blocks.
  • 2.2.2 26 September 2025
    • Adjust Settings UI layout for macOS 26.
  • 2.2.1 16 September 2025
    • Add macOS 26 icon.
    • Add macOS 26 menu items.
    • Mitigate macOS 26 NSSlider changes.
    • Apply button correctly highlights on theme change.
  • 2.2.0 9 September 2025
    • Add new UI for YAML front matter.
    • Expand size of preview window.
    • Add a Convert Markdown Text to Plain Text system-wide text service.
    • Restore the original settings icon.
    • Migrate to TextKit 2.
    • Fix NSColor.hexToColour() alpha handling.
    • Fix image src extraction in certain cases.
  • 2.1.0 28 August 2025
    • Add whitespace margin around previews, with option to disable in Settings.
    • Allow the colour of front-matter YAML keys to be changed in Settings.
    • Update the design of the What’s New panel.
    • Fix disabling/re-enabling of Settings menu item when sheets open/close.
    • Fix extraneous \n added by Markdown-It after including pre-formatted HTML.
    • Reorganize and consolidate constant values.
  • 2.0.0 1 August 2025
    • Introduce a new rendering engine which leverages Markdown-It.
    • Now supports tables, highlighted code blocks, image placement, multiple styles in blockquotes, and more.
    • More fully support escaped characters in Markdown.
    • Introduce a new tab-based UI for the host application.
    • Add a Convert Markdown Text to HTML system-wide text service.
  • 1.5.3 7 September 2024
    • Improve settings change checking.
    • Correctly render the YAML frontmatter separator line.
  • 1.5.2 13 May 2024
    • Revise thumbnailer to improve memory utilization and efficiency.
  • 1.5.1 2 November 2023
    • Support the emerging public.markdown UTI.
    • Support YAML front matter that uses the ... end marker (Thanks, anonymous).
    • Better What’s New dialog presentation in dark mode.
  • 1.5.0 1 April 2023
    • Add preview line spacing control.
    • Add help button to Preferences panel.
    • Add experimental Finder UTI database reset option.
    • Remove dynamic UTIs.
  • 1.4.6 21 January 2023
    • Add link to PreviewText.
    • Better menu handling when panels are visible.
    • Better app exit management.
  • 1.4.5 23 December 2022
    • Add UTI com.nutstore.down.
  • 1.4.4 2 October 2022
  • 1.4.3 26 August 2022
    • Initial support for non-utf8 source code file encodings.
  • 1.4.2 7 August 2022
    • Support GitHub-style checkboxes [ ] [x].
    • Update to SwiftyMarkdown 1.2.4.
  • 1.4.1 20 November 2021
    • Disable selection of thumbnail tags under macOS 12 Monterey to avoid clash with system-added tags.
  • 1.4.0 28 July 2021
    • Allow any installed font to be selected.
    • Allow the heading colour to be selected.
    • Allow any colour to be chosen using macOS’ colour picker.
    • Tighten the thumbnailer code.
    • Fixed a rare bug in the previewer error reporting code.
  • 1.3.1 17 June 2021
    • Add links to other PreviewApps.
    • Support macOS 11 Big Sur’s UTType API.
    • Stability improvements.
  • 1.3.0 9 May 2021
    • Add optional presentation of YAML front matter to previews.
    • Recode Thumbnailer to make it thread safe: this should prevent crashes leading to generic or editor-specific thumbnail icons being seen.
    • Update user-agent string.
    • Minor code and UI improvements.
  • 1.2.0 4 February 2021
    • Add preview display preferences (requested by various anonymous feedback senders).
    • Add file type ident tag to thumbnails (requested by @chamiu).
    • Add What’s New sheet to be shown with new major/minor versions.
    • Include local markdown UTI with user-submitted feedback.
    • Add link for app reviews.
  • 1.1.4 16 January 2021
    • Add UTI net.ia.markdown.
  • 1.1.3 13 January 2021
    • Add UTI writer.pro.markdown.
  • 1.1.2 18 November 2020
    • Apple Silicon support.
  • 1.1.1 1 October 2020
    • Add report bugs/send feedback mechanism.
    • Add further usage advice to the main window.
    • Handle markdown formatting not yet rendered by SwiftyMarkdown: three-tick code blocks; HTML symbols; space-inset lists.
  • 1.1.0 25 September 2020
    • Add macOS Big Sur support.
    • Better macOS dark/light mode support.
    • Migrate engine to SwiftyMarkdown 1.2.3.
  • 1.0.5 9 April 2020
    • Mac App Store version.
  • 1.0.4 Not Released
    • No user-visible changes.
  • 1.0.3 10 December 2019
    • Add the version number to the app info dialog.
  • 1.0.2 4 December 2019
    • Fix random crash (string index out of range in SwiftyMarkdown).
  • 1.0.1 20 November 2019
    • Correct thumbnail styling.
  • 1.0.0 8 November 2019
    • Initial public release.

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