You can developer-unlock any Windows Phone by installing the “Windows Phone Developer Registration” tool from the SDK. This is the most common method.
Note: This method usually only works if the app is free (which WhatsApp is) and if the phone's date settings are within the app's valid period. The OS may refuse to install the app if it detects it is incompatible with the OS build number. download whatsapp xap file for windows phone
Unfortunately, for the standard WhatsApp experience, there are no working workarounds for Windows Phone 8.1 or older. windows phone xap files - Microsoft Q&A You can developer-unlock any Windows Phone by installing