Beat is a free and open source screenwriting application for macOS (10.10 or higher). It uses Fountain screenplay format and aims to be minimalistic and distraction free.
I pretty much hated every screenwriting app there was, so I had to create one of my own. The project is originally based on Writer, an older open source Fountain editor.
Beat is under active development – whenever I have the time and energy.
Read more on the Beat website. You can support the development (or rather, paying the hosting costs) by buying it on itch.io for any price you want.