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

Latest Release: 1.5.3

 

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: just click OK:

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:

You can disable or re-enable Markdown Previewer and Markdown Thumbnailer in System Preferences > Extensions:

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.

Back to the Top

Customise the Preview

The app’s Preferences panel allows you 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 code blocks.
  • The colour of headlines.
  • Whether YAML front matter should be included in previews.
  • 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 you want regular text and code to be presented in. You can also choose each font’s style:

Choose your preferred heading and code colours by clicking the appropriate colour well to pop up macOS’ colour picker. As you make your colour selection, the colour well will be updated:

Click Save to apply your choices.

Changing these settings will affect previews immediately, but may not affect 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.

Back to the Top

Feedback and Bug Reports

You can use the in-app UI to submit feedback or contact me. Just click in the Send Feedback button in the main window, or select Report a Bug… from the Help menu:

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.

Back to the Top

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 (i) symbol alongside the Quick Look entry under Extensions. Make sure Markdown Previewer and Markdown Thumbnailer are both switched on (see image 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.

Back to the Top

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!

Back to the Top

Acknowledgements

PreviewMarkdown makes use of code from the following sources:

Back to the Top

Source Code

You can view PreviewMarkdown’s source code at GitHub.

Back to the Top

Release Notes

  • 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.

Back to the Top

Related Software

Back to the Top

smittytonesmittytone
Site and software copyright © 2025, Tony Smith