Here is a detailed guide on how you can send Whatsapp messages without adding a contact on an android device. Many of us believe it is not possible to send the message without saving the number in the phone contacts, however, there is a way in which you can send WhatsApp messages to a number that is not saved in your contacts.
Step 1: Open your web browser on your android device.
Step 2: Copy and paste this link in the address bar on your browser: https://api.WhatsApp.com/send?phone=number
Step 3: In the place of “number” in the above link, enter the phone number with the country code of the person to whom you want to send a message
Step 4: After you enter the link given above, the Whatsapp webpage will load.
Step 5: Whatsapp will ask you to continue to Chat, click on it then your WhatsApp app will open for the said mobile number.