The Free plan is genuinely free — no credit card required. Sign up with just an email and password and you get up to 2 pilots, all five core boards (including Card View), all five pilot templates, cloud sync, and Word/PDF export.
Pro is an optional paid upgrade ($6.98/mo or $69.98/yr) that removes the pilot limit and adds Deep Dives, Additional Cast, project sharing, and Final Draft/Full Character Bible export. See "What's the difference between Free and Pro?" for the full breakdown.