There is several commandline tools, ffmpeg and ffmbc. And there is frontends to these too: Cinec and my favorite AnotherGUI. But they can sometimes in my experience add some white frames to the end of files so i dont trust to use them for any delivery files for endclients, only if i deliver files for FCP editors that have to use them for inserting in an edit.

There is some highend Windows based tools that has licensed ProRes from Apple, eg. Telestreams expensive server based tools, Quantel Pablo and i guess a few others.

Keep bugging Adobe to come up with a good alternative that could replace both ProRes and DNxHD as industry standard codec is the ultimate solution in my dreams. Maybe we will see it some day, it should be possible to do an improvement on ProRes/DNxHD that are almost 10 years old technology, right?