.icns

Apple icon image, the multi-resolution icon resource format used for macOS application icons

Handled by macOS itself

Format facts

MIME type: image/x-icon
Apple UTI: com.apple.icns
Stock Quick Look: no stock preview
Planned approach (census): native-sufficient
Icon hint: renders
Prevalence: universal

Renderer note (from the census)

macOS renders ICNS natively