Repl Multiplayer is there to help ya.

You could use multiplayer like others have mentioned along with a chat app such as (discord)[https://discordapp.com] which is 100% free and you can chat with text, voice, and video on all your devices. I am not sponsored by discord in any way, I just love it.

If you click he icon with the 2 people, you can turn your repl into a live one. What that means is 2 people can edit the files, at the same time. Only people you share this link with can do this however.

(after clicking start session)