FM WhatsApp (often abbreviated FMWhatsApp) is an unofficial, modified version of WhatsApp created by third-party developers that adds extra features not found in the official app (custom themes, extended privacy toggles, message scheduling, larger file limits, and UI customizations). “APK 963 patched” refers to a specific patched build/version circulating as an installable Android package (APK) that claims to include additional fixes or unlocked features.