IIRC, you can set a Google Doc to be edited by anyone with a direct link to it, so that's pretty much the same as what you're after, isn't it?
OK, it's not embedded on this forum, but that's a minor detail really.
read fluently, understand well, speak badly;
read fluently, understand badly, can't speak;
read some, understand a bit, speak a few sentences;
heritage language, want to understand and speak but can't.