DXO is currently on version 11 of its rather excellent image editing software, Optics Pro. However, if you don’t need the latest and greatest, you can actually get Optics Pro 9 completely free until February 28th, 2017.
Be sure to check and see if your camera is supported before downloading, because not all of the new models are in there. But, you can get an idea of how the software works, and if you’re using an older model, you get access to tools like the Prime noise reduction utility for zero dollars. If you haven’t used Prime, it’s very good, if a little time consuming.