River Writer is a free Mac app for screenplays, stage plays and novels. You write plain text (.fountain or .md) and a live preview shows the formatted, print-ready pages beside it: Screenplay, Multi-cam, Stage Play or Manuscript. Git versioning is built in, so you can commit drafts, restore files and try an alternate ending on a branch. Outline, scratchpad and todos live as plain files in your project. No accounts, cloud, telemetry or AI; it makes no network connections. Open source (MIT).