Hi folks, This is a software I've been using for over a year now. It's a fantastic free replacement for basically every other screenwriting software. It's fully-featured with full collaboration tools (I would know, I've used them).
The Pro version costs...a bit. I bought it when it was like $30, but the only super-awesome feature I've used for the pro version is the desktop app. Otherwise, the free version is perfect for pretty much everyone, although the pro version has some nice but not necessary at all features.