Super simple no-code for web apps

Hi guys! I am working on a community where users can create their chat rooms and discuss specific topics. Is there any very simple no-code web-app tool I could try? I was working with bubble, but it takes a lot of time to set up correctly as it is very customizable, and you have to make the responsive design yourself. I don't need any customization. Just authentification, creating items, and listing items. Does anybody have something on mind?