Quick Look plugins 
List of useful Quick Look plugins for developers
Install
Using Homebrew
- Run
brew install <package>
Catalina notes
To get many plugins working in Catalina and later, 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
Manually
- Click "download manually"
- Move the downloaded .qlgenerator file to
~/Library/QuickLook
- Run
qlmanage -r
Plugins
QLStephen
Preview plain text files without or with unknown file extension. Example: README, CHANGELOG, index.styl, etc.
Run brew install qlstephen or download manually

QLMarkdown
Preview Markdown files
Run brew install --cask qlmarkdown or download manually

QuickLookJSON
Preview JSON files
Download manually

BetterZipQL
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.

Suspicious Package
Preview the contents of a standard Apple installer package
Run brew install suspicious-package or download manually

Apparency
Preview the contents of a macOS app
Run brew install apparency or download manually

QLVideo
Preview most types of video files, as well as their thumbnails, cover art and metadata
Run brew install qlvideo or download manually

Source Code Preview 💰
Includes 10+ color themes and syntax highlighting for 50+ languages, including JavaScript, Python, Java, CSS, and JSON.
Purchase on the App Store.

Peek 💰
Peek allows you to copy and find text, jump to line numbers, render Github-flavored Markdown with a generated table of contents, restore scroll positions, highlight syntax, & more in the Quick Look previews of over 300 file extensions.
Purchase on the App Store.
The app is abandoned and buggy, but still functional.

Folder Preview 💰
Quick look inside folders and archives.
Purchase on the App Store.

Folder Quick Look 💰
Preview folder and archive contents (ZIP, RAR, and more).
Purchase on the App Store.

FluxMarkdown
Preview Markdown files with Mermaid diagrams, KaTeX math, GFM support, and interactive table of contents.
Run brew tap xykong/tap && brew install --cask flux-markdown or download manually

Markdown Preview 💰
Quick look Markdown files with KaTex and Mermaid support.
Purchase on the App Store.

EPS Preview 💰
EPS Preview adds Quick Look and thumbnails of EPS files to Finder.
Purchase on the website.

ProvisionQL
Preview iOS / macOS app and provision information
Run brew install provisionql or download manually

WebP
Preview WebP images
NOTE: This is already covered by qlImageSize, so this plugin is listed here only in case you do not like qlImageSize.
Run brew install webpquicklook or download manually

SourceCodeSyntaxHighlight
Preview many different source code files
Run brew install --cask --no-quarantine syntax-highlight or download manually

Note: This might overwrite some other Quick Look plugins.
Burrete
Preview PDB, mmCIF, SDF, XYZ, trajectories, and chemistry tables in Finder
Download manually

Preview3MF
Preview 3MF 3D-printing models — real 3D rendering plus Finder thumbnails
Run brew install --cask cavoco/tap/preview3mf or download manually

License

To the extent possible under law, Sindre Sorhus has waived all copyright and related or neighboring rights to this work.