Kiview lets you quickly preview various file types (text, images, videos, etc.) in Dolphin without opening the default app. Similar applications are Apple's Quick Look and Gnome Sushi.

Supported file types:

.txt,.sh,.json,.pdf,.doc,.docx,.odt,.ods,.xlsx,.xls,.csv,.odp,.ppt,.pptx,.png,.jpg,.jpeg,.jxl,.kra,.svgz,.svg,.mp4,.mp3,.webm,.zip,.gz,.xz,.rar