What camera to buy ? i need a camera for Twitch and YouTube 4k videos.

So no one know ?

Well it might be a stupid question from me but don't people use software to record stuff for Youtube or Twitch?

For 4K video of yourself (I assume...) it totally depends on what your budget is.

are you looking for an actual camera with 4K capabilities? or software that records gaming at 4k quality? Those are two drastically different things.

4k isn't that viable yet due to computing and internet speeds. Twitch has a maximum bitrate limit of 3500. Even if you stream on 4k it's not going to look great at all and unless you are a partner you will have a very very small audience that can watch it smoothly anyway. I'm not sure if you mean software or webcam, but I recommend just capturing in 4k and downscaling it. It's still 1080p on youtube but you gain some visual fidelity.

The cheapest 4k camera you can get right now is a Go Pro 4. You can get by just fine with 1080p, though. So buying a used Go Pro 2 or 3 is a viable idea for ya.