When you sign up for WhatsApp, you are required to provide your phone number, which is used as your primary identifier on the platform. However, beyond your phone number, you do not need to share any additional personal information to use WhatsApp.

WhatsApp does not require you to provide your name, email address, or any other identifying information. You can use a pseudonym or nickname as your display name on the platform, which can help protect your privacy.

In terms of data sharing, WhatsApp does collect some user data, such as your phone number, device information, and usage data, but the platform is designed to use end-to-end encryption, which means that your messages and calls are secured and cannot be accessed by WhatsApp or third parties.

WhatsApp also has a privacy policy that outlines how it collects and uses user data, and users can opt out of certain types of data sharing, such as sharing their account information with Facebook.

That being said, keep in mind that the contacts you communicate with on WhatsApp will be able to see your phone number and display name, so if you want to maintain complete anonymity, you may want to avoid sharing any personal information with contacts on the platform.