As of , the current requirements for WhatsApp are as follows: Minimum OS : Android 5.0 (Lollipop) or newer is required.
The message didn't have a double blue tick. It didn't show "typing..." in real-time. It just worked. For one afternoon, the old slab of plastic and glass wasn't obsolete. It was a bridge to a time when a "ping" meant someone was thinking of you, not that an algorithm was demanding your attention. Download Whatsapp Old Version For Android 2-3-6
While you can find and install an APK file compatible with older hardware, the service itself will block access for several reasons: Server-Side Block As of , the current requirements for WhatsApp