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

Not wanting to pay a hefty license fee led me away from Ableton and into the loving arms of Renoise. It has an unlimited free trial with no restrictions, but a full license is $80 per FULL POINT RELEASE. That is: if you pay at v3.2, you don't pay again until v4.2. I paid once in 2012 and still haven't paid again yet. So it's cheap. But it's also fully featured, and surprisingly powerful. It's got a scary UI and... Source: almost 2 years ago

If you're in to music creation, give it a go. http://renoise.com. Source: over 2 years ago

There's plenty of software available for PC so it's easy to try out if tracker workflow is your thing :P I think Renoise is the most popular and most powerful tracker and there's a free demo available in https://renoise.com. Source: over 2 years ago