Darktable is a free and open-source photography workflow application and raw developer.

LightZone is a free, open source digital photo editor software application.

ExifTool is a free and open-source software program for reading, writing, and manipulating image, audio, video, and PDF metadata.

UFRaw (Unidentified Flying Raw) is an application which can read and manipulate photographs in raw image formats, as created by many digital cameras.