Can someone add me to a WhatsApp group without asking?

Being added exposes your number, name and photo to every group member — that is a disclosure of personal data, and who did it decides the law. Friends and family: the household exemption covers purely private social life — annoying, not illegal; leave quietly. Businesses, clubs, schools, landlords, sales groups: different story. An organisation adding customer or member numbers to a group needs a lawful basis, and “we had your number from the invoice” is not one — DPA guidance across Europe treats mass-adding as unlawful disclosure, and marketing via group messages without opt-in breaks the ePrivacy marketing rules on top. The right pattern (used by decent schools and clubs): announcement-only broadcast lists, or asking before adding — see the club rules. Lock it down once: WhatsApp → Settings → Privacy → Groups → “My contacts” (or “My contacts except…”) — strangers then need to send an invite you can ignore. Escalation for repeat business offenders: leave + report the group, object under Art. 21, demand deletion of your number from their marketing set, and a DPA complaint for the stubborn — group-blast marketing complaints are routinely upheld.