WhatsApp does not allow users to send messages to contacts that have not been saved on the phone which many users find annoying. However, now there is a trick that allows users to send messages to people who are not in their phone book.
Following are the steps to send Whatsapp messages without adding the contact to address book –
1.) Open your Phone’s web browser and paste the following URL in the Address bar.
Link - https://api.WhatsApp.com/send?phone=number
2.) In place of ‘number’ in the URL above, type the phone number of the person to whom you want to send a message with the country code.
3.) If you're sending it to an international number, omit any zeroes, brackets or dashes in the URL when typing the phone number.
4.) A point to note is that the number you want to send a message to should be an active user on WhatsApp.
5.) After you have followed the above step, click on the message button on the website and you will be directly taken to WhatsApp with a chat being open for the given contact number.