Photivo

Photivo is a photo-editing tool with a very simple and unique interface that lets you access all its features from a sidebar on the left.

The program supports images in popular formats, as well as uncompressed RAW photos. It lets you apply all kinds of layers and effects before importing them into GIMP, which is completely integrated with Photivo.

Another interesting feature is the ability to retouch images by the batch and upload entire folders of photos, though they may take some time to be fully processed.

Photivo is an interesting image-editing program that's basically essential for any GIMP user who loves photography.