WhatsApp Web, Service is currently available for users on the Android, Windows Phone and BlackBerry platforms, iOS compatibility isn't on the way for now.
This service is only accessible via the Chrome browser for desktop and its Android based app. Mac users cannot access WhatsApp Web via Safari, but can use Chrome for that very purpose, and the iOS version of the Big G’s Web browser isn’t supported either. According to the WhatsApp team, support for more browsers is likely to be coming soon.
Step 1: Be sure that you are running the latest version of WhatsApp on your smart-phone.
Step 2: Head over to the http://web.whatsapp.com URL, where you will be greeted with a QR code that needs to be scanned.
Step 3: The webpage also lists where you can access the WhatsApp Web option on your Android, BlackBerry or Windows Phone device. Tap that option on your phone’s WhatsApp client, which will launch the QR code scanner.