In short

The way we all are using Whatsapp is illegal in the GDPR (EU) and FADP (Switzerland) areas.

Detailed

Whatsapp is uploading your address book contact's data to their servers.
- Phone numbers, and maybe names and email-addresses
- All contacts, not only those using Whatsapp
- On a daily basis

When you first use Whatsapp, you reach a page where you have to accept the global terms. In these terms, the address book sharing is explained, and with the [Accept] button, you accept the responsability for this illegal behaviour.

Before accepting these terms and start using Whatsapp you first need to ask all your contacts if they accept that you share their contacts with the Whatsapp servers.
This authorization must not be "passive" (opt out): You may not make a general Whatsapp or eMail like "If you don't agree that I share your data, please reply to me", but must be "active" (opt in): Every person in your address book must give you his individual authorization to share his data!

Questions: - Have you read the global terms before clicking "Accept"? - Have you got all your contact's authorization for sharing their data?

So, what to do?
- Delete your Whatsapp account   or
- In your address book, delete all your contacts that did not give their authorization.

I'll continue to use one legal, safe and confidential messenger: Threema  -  79M5AYS5 Swiss made - by far the worlds best, safest and most private messenger (Only 6 €/CHF for lifetime) What about Signal and RCS(SMS) ? They are using US cloud systems (Amazon AWS, Microsoft Azure, ...) which are subject to the "US cloud act" and thus are not private.

Written/edited by Paul