WhatsApp itself does not allow sending anonymous messages. If you look for this option in any of the application menus, you will see that it does not exist. In order to be able to use this feature, it is necessary to resort to other solutions.
For a while, the use of a web service called Wassame, which theoretically allowed sending anonymous messages to WhatsApp numbers, caught on. The point is that this service doesn’t work though. The only thing we get when trying to send an anonymous message with it is sharing a third party’s number and a website of unknown purpose.
Another possibility, which does not guarantee anonymity but at least allows using a number unknown to the recipient, is using a second SIM card, to which you can copy the phone number you want to send WhatsApp to. You can then take advantage of the fact that the recipient doesn’t know your second calling card to send them a pseudo-anonymous message.
If a second SIM card is too much trouble for you, you can always try applications like eSIM Number to get a second virtual phone number that you save in your phone. However, these numbers are chargeable and require a subscription. Please note that not all numbers offered by these services are mobile numbers (some only offer landlines), so you’ll need to do some research before settling on one.
The closest you can come to communicating anonymously with another person is to use other chat and messaging applications that allow you to communicate using a user ID without sharing a phone number or email. Among the most popular for this you will find some like Telegram or LINE.
There is a bot in Telegram that allows users to send messages to other users without revealing their identity, but it works more like a kind of chat roulette than a way to send messages to your contacts:
Incognito Telegram bot
As you can see, the solution is far from ideal. Most of the applications that advertise themselves as anonymous messaging solutions, like Psst or Whisper, work very similar to this bot. Currently it is rather very complicated to send messages to our contacts anonymously (either with WhatsApp or with another application) .