Lightroom is a program from Adobe that I use all of the time, though I don't have a freestanding version, I start it from Adobe Bridge (if I have Photoshop open and I click on a DNG file, it also automatically opens Lightroom). That program is excellent.

Some time ago Google bought a photo processing company and for a while made it free. The Nik Collection was sold to a new company and they still let you download the earlier software for free. I've never tried it, but heard good reports. Here's an article: Google’s Free Photo Editing Software, the Nik Collection, Has Been Acquired by DxO & Will Live Another Day