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 / 6 months ago

Not open source, but free for "home use" https://virtualdj.com/. - Source: Hacker News / 6 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: almost 2 years 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

Would like to throw in https://festify.rocks. Source: about 1 year ago

Is there any alternative to https://festify.rocks/ that works for youtube music? Source: over 1 year ago

Nice idea but isn‘t it the same as https://festify.rocks/ If not, where is the difference? Source: over 1 year ago

Probably not what you're looking for if you want to host the music files themselves too, but https://festify.rocks is a web-based democratic jukebox software that uses Spotify for the music. Source: about 3 years ago