Web-based libre software for video chat

I know for sure that I'm looking for libre video chat software that has these features for the other person, not necessarily for me:

• no need to create an account
• mobile-friendly web app

I'm still deciding whether to do video chats on:

• iPhone
• Fedora GNU + Linux (GNOME)

Use case: I'm considering switching from text to video chat as my preferred method for initial conversations with people on dating sites/communities. There's not always a sacrifice of convenience by avoiding non-libre software for it, because whatever app is already being used typically only integrates messaging, not video chat.