Mobile website WhatsApp button to send message to a specific number

 Format to send a WhatsApp message to a specific number (updated Nov 2018)

<a href="https://wa.me/whatsappphonenumber/?text=urlencodedtext"></a>

whatsappphonenumber is a full phone number in international format

urlencodedtext is the URL-encoded pre-filled message.

 

Example:

Send I am interested in your car for sale to +001-(555)1234567

https://wa.me/15551234567?text=I%20am%20interested%20in%20your%20car%20for%20sale 

Note :

Use: https://wa.me/15551234567

Don't use: https://wa.me/+001-(555)1234567