Student or Learner
I uploaded pictures <to/in/on> a chatting room.
Is that sentence correct?
If I upload something to a group chatting room on Whatsapp, which preposition should be used when using "upload"?
You can upload things to the internet or to any site which occurs on the internet. I would use "to" in your context though I would add that "on" is not entirely wrong. Note that it's "chatroom", not "chatting room".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.