RawTherapee

RawTherapee is a raw photo developer for turning files from a broad range of digital cameras into finished images. It also handles HDR DNG files and non-raw formats like JPEG, TIFF, and PNG, so it can serve as a general editing tool too.

Its strength is depth of control. A patched build of dcraw reads raw files, backed by an in-house decoder that adds the highest-quality support for certain camera models and improves accuracy on others. From there you get fine-grained command over the demosaicing and development process.

RawTherapee is aimed at users from enthusiasts to semi-professional photographers, and it deliberately leaves out asset management, printing, and uploading to stay focused on development. It runs on Windows, macOS, and Linux as free software under the GNU GPL v3.