Consent is a key factor of GDPR legislation, which offers individuals a choice and control over how their data is used, with a desire to build their trust and engagement. Your web-portal which collects personal data must make visitors understand exactly how you are planning on using their personal information. They must then agree to each specific purpose. Even if you have someone's email address, phone number, and credit card information after they use a shopping cart feature, you are not allowed to share this information without their agreement.
WhatsApp now lets users see the data that it collects from them.