But just use https://live365.com/ they do the streaming and royalties for you. Source: over 1 year ago

I subscribed to Live365, which is a turn-key radio broadcasting platform that includes music licensing for the USA, Canada, UK. I've purchased over 850 tracks from Amazon, Beatport, Bandcamp, and 7digital, and listed the station in multiple radio/podcast directories. Since launching the station two weeks ago, we have attracted about 20-30 daily listeners, done 2 DJ mix sessions, 1 on location live broadcast, 1... Source: almost 3 years ago

Mixxx is excellent and has pretty wide hardware support. FYI the "limited" functionality of Rekordbox can be hardware unlocked with some Pioneer controllers. https://mixxx.org/. - Source: Hacker News / 5 months ago

There are quite a few DJs that use Ableton for DJing (or hybrid sets). Of course, Ableton wasn't made with DJing as its main function in mind but you totally can use it for that purpose and (with some tweaking) do everything and more that would be possible in a dedicated DJing software (like Traktor or Rekordbox or Mixxx). Source: about 1 year ago

I’ve used Mixxx a little bit and have been surprised how capable it is. It’s an open source project and is free to download: https://mixxx.org/. Source: about 1 year ago

Mixxx (you already mentioned this; it's certainly a great piece of free software to test the DJ waters with and works with a lot of gear). Source: about 1 year ago

Alternatively, you can also use Mixxx with the S4 MK2. Mixxx is free. But instead of a Traktor control vinyl record, you'd use Serato timecode instead, as stated in the docs. Source: about 1 year ago