List of useful Quick Look plugins for developers
brew install <package>brew install qlcolorcode qlstephen qlmarkdown quicklook-json qlimagesize suspicious-package apparency quicklookase qlvideo
    To get plugins working in Catalina, you will need to remove the quarantine attribute.
Run this to see the attributes:
xattr -r ~/Library/QuickLook
    And run this to remove the attributes:
xattr -d -r com.apple.quarantine ~/Library/QuickLook
    ~/Library/QuickLook
      qlmanage -rPreview source code files with syntax highlighting
      Run brew install qlcolorcode or
      download manually
    
Preview plain text files without or with unknown file extension. Example: README, CHANGELOG, index.styl, etc.
      Run brew install qlstephen or
      download manually
    
Preview Markdown files
      Run brew install qlmarkdown or
      download manually
    
Preview JSON files
      Run brew install quicklook-json or
      download manually
    
Preview archives
Note: The BetterZipQL plugin was integrated with the BetterZip app.
      Run brew install betterzip to install the BetterZip app and
      its Quick Look plugin or
      download manually
    
The legacy BetterZipQL plugin can be downloaded here.
Display image size and resolution
      Run brew install qlimagesize or
      download manually
    
Preview the contents of a standard Apple installer package
      Run brew install suspicious-package or
      download manually
    
Preview the contents of a macOS app
      Run brew install apparency or
      download manually
    
Preview Adobe ASE Color Swatches generated with Adobe Photoshop, Adobe Illustrator, Adobe Color CC, Spectrum, COLOURlovers, Prisma, among many others.
      Run brew install quicklookase or
      download manually
    
Preview most types of video files, as well as their thumbnails, cover art and metadata
      Run brew install qlvideo or
      download manually
    
These are not included in Install all.
Preview iOS / macOS app and provision information
      Run brew install provisionql or
      download manually
    
Preview Android APK files
      Run brew install quicklookapk or
      download manually
    
Preview Adobe Photoshop pattern files
      Run brew install quicklook-pat or
      download manually
    
Preview WebP images
NOTE: This is already covered by
qlImageSize, so this plugin is listed here only in case you do not likeqlImageSize.
      Run brew install webpquicklook or
      download manually
    
To the extent possible under law, Sindre Sorhus has waived all copyright and related or neighboring rights to this work.