PreviewQt

PreviewQt is a simple applications that allows you to preview all kinds of files, from images to videos, from documents to archives, and also text files of any kind. It is based on Qt/QML, published as open-source, and completely free.

Supported file formats include:

• More than 140 image formats - A list of all possibly supported image formats can be found on the website for PhotoQt: https://previewqt.org/formats
• All of the common video formats
• Photo spheres and 360 degree panoramas (that use equirectangular prohections)
• Motion photos, Micro videos, and Apple live photos
• PDF documents including page navigation
• Archives (zip, tar.gz, rar, 7-zip) with the ability to explore its content
• Comic Books (cbz, cbt, cbr, cb7) including page navigation
• Text files of all kinds including syntax highlighting and search

It is also possible to set up an external application for the categories of files. With a shortcut or button it is possible to pass a previewed file on to the provided external application for further processing.

If you like the overall concept of PreviewQt but would like to have more features, check out the fully featured image viewer PhotoQt: https://photoqt.org