qimgv is a customizable image viewer with optional video support. It supports basic image editing such as crop, rotate and resize, as well as copy / move operations of images to different folders. Supports modern image formats JPEG, GIF, PNG, APNG, RAW, MP4, WEBM, etc.
The program aims for an uncluttered user interface, i.e. you see UI elements only when you need them. There is a pull-down panel with thumbnails, as well as folder view (accessible by pressing Enter). You can also bring up a context menu by right-clicking on an image.
Cross-platform with clients available for Linux and written in Qt.