world

World ID gives an application a bounded proof about a person—such as uniqueness, liveness or possession of a supported document—without supplying that application with the underlying biometric or document data. It is designed for one-person-one-action controls rather than a reusable government-service login.

The World App produces application-specific proofs

The World App holds the user-side identity material and generates proofs on the device. Proof of Human follows Orb verification and represents the higher-assurance unique, live-person credential; document credentials use supported NFC government documents, while Selfie Check is a lower-friction beta route.

A proof carries a nullifier derived from the user, the relying application and the requested action. The same person gets the same nullifier for that action in that app, but different apps or actions receive different values, allowing duplicate prevention without a cross-app identifier.

Verification is an application responsibility as well as a proof check

A relying party signs a proof request, the user meets its credential requirement in the app, and the backend verifies the response through the integration flow. The application must retain and reject an already used nullifier before treating an action as one person, one time.

It also chooses the action context, accepted credential, user-presence requirement and legacy-proof policy. A valid proof alone does not enforce a giveaway, vote or account rule if the application does not bind and store those values correctly.

Privacy and recovery have different trade-offs

Zero-knowledge proofs keep the requested property separate from the raw personal data used to obtain a credential, while multi-party computation divides matching and uniqueness checks across independent nodes. That privacy design does not remove the application’s need to protect its own request-signing key and verification policy.

World Chain offers an optional contract-verification path, where the contract must likewise bind request values and record used nullifiers. Recovery depends on a previously configured passkey, Apple or Google login; without such a method, World App cannot restore lost passwords or passkeys, and a security delay can restrict sensitive actions during recovery.