Vauchi

Privacy-focused updatable contact cards. Exchange contact information in person via QR code, with end-to-end encryption. When you update your phone number or email, everyone who has your card sees the change — without any central server having access to your data. Uses Signal protocol cryptography (X3DH + Double Ratchet) with an oblivious privacy-preserving relay. Self-hostable; no accounts, no phone number, no social graph.