To "live DJ" there's the extremely famous https://virtualdj.com/ To create prerecorded DJ sets https://www.mixmeister.com/ Been using both for at least 10 years, love them both. - Source: Hacker News / 5 months ago

Not open source, but free for "home use" https://virtualdj.com/. - Source: Hacker News / 5 months ago

I started with Virtual DJ to get used to the software latency (I came from turntables) and get my muscle memory on button locations (which is why I stayed with the same brand). VDJ has every feature you need. The software is free to use without a controller from virtualdj.com. Source: over 1 year ago

A lot of the places that do it from scratch I notice use https://virtualdj.com/. Source: almost 2 years ago

DJ software, like VirtualDJ will have features that are more conducive to what you're trying to do, like live looping functions that help you lock the loop to the beat. It's also cheaper (free for non-commercial use without a hardware controller) than QLab, and it's cross-platform (QLab is Mac-only, if that matters). Source: about 2 years 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