Open in WhatsApp 
- This app uses WhatsApp public api 'click to chat' feature to open a chat with any number without saving to your phone book.
- You can create an url link that will open WhatsApp on the specified number. This is a WhatsApp feature, you don't need this app to open the link, only to create it.
Download
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Thanks
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ialokim for android-phone-number-field which is license under Apache-2.0,
License