I've developed a nice GUI application which can filter whatsapp numbers from millions of phone numbers in few seconds.
You can see a video for the same - [url removed, login to view]
I want to sell this app at a very low price.
If anyone out there is interested then please place bid and I'll contact you.
Video link is here - www.dropbox.com/s/90edtksqr6n5kpn/WhatsApp%20Contact%20Filters-04-09-2014-06-46-51.mp4?dl=0