Features I'm looking for:
- No registration needed for group members. If one person has to register and own the chat room that would be ok.
- A way to easily share the chat room. I can't think of anything more convenient than a link, but I'm open to other solutions as long as non-technical people would find it easy.
- Persistent. Folks can enter and exit the same chat and see the history.
- Chat room can eventually be deleted when no longer needed.
- Browser based with no additional software to install.
- Open source is always nice.
No registration would be required and TheLounge provides chat persistence. Both are open source. Visitors would not need to be technical and would not need to know IRC commands. Rooms can be deleted by the channel operator. Clients of TheLounge require only a browser and do not require any additional software. The IRC daemon scales to tens of thousands of people on a small server. Adding a web front-end reduces that number a little.
[1] - https://www.unrealircd.org/ https://github.com/unrealircd/unrealircd/
This one is the most troublesome I think.
Usually this is in a conferencing solutions though, so no such thing as chat rooms, I think.
Otherwise I would suppose something like XMPP with a web frontend, eg https://movim.eu/
ejabberd supports anonymous users, though I can't say if movim or any else web-client supports that natively
Here is a example chat I created.