World ID is a decentralized identity protocol that enables users to prove they are a unique human without revealing their personal identity, a concept known as proof of personhood. It uses zero-knowledge proofs (ZKPs) and biometric verification via the World App to issue a World ID, which acts as a global, anonymous credential. This system aims to solve the problem of digital identity fraud and Sybil attacks—where a single entity creates many fake accounts—by cryptographically verifying that each ID corresponds to one real person.
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Glossary
World ID
A global, privacy-preserving digital identity network that uses zero-knowledge proofs to verify an individual's unique personhood.
Chainscore © 2026
definition
DECENTRALIZED IDENTITY PROTOCOL
What is World ID?
World ID is a privacy-preserving digital identity protocol designed to verify human uniqueness on the internet.
The core mechanism involves a user verifying their uniqueness through an orb, a specialized biometric imaging device, which creates an IrisCode. This code is used to generate a zero-knowledge proof that the user is human and unique, without storing the biometric data itself. The resulting World ID is stored in a user's digital wallet, such as the World App, and can be used to anonymously authenticate with applications and services that integrate the protocol, often to access features like airdrops, governance rights, or exclusive content.
Developed by Tools for Humanity, the protocol operates on the World Chain, an Ethereum Layer 2 blockchain optimized for human-centric applications. For developers, integrating World ID provides a trustless way to ensure their applications are interacting with real individuals, enabling use cases in democratic governance (e.g., one-person-one-vote systems), fair distribution of resources, and bot-resistant social networks. The protocol's architecture emphasizes privacy-by-design, ensuring that personal data is never linked to on-chain activity.
how-it-works
TECHNICAL ARCHITECTURE
How World ID Works
World ID is a decentralized identity protocol that uses zero-knowledge proofs and biometric verification to create a global, privacy-preserving proof of personhood.
World ID operates on a three-component architecture: the World App (wallet), the Worldcoin Orb (biometric verification device), and the World ID Protocol (on-chain infrastructure). A user downloads the World App, which generates a cryptographic key pair. To prove their unique personhood, they visit an Orb for an in-person iris scan. The Orb uses specialized sensors to create a unique IrisHash—a one-way cryptographic representation of the user's iris pattern—which is checked against a global database to prevent duplicate registrations. If unique, the Orb cryptographically signs a claim of uniqueness, which is relayed to the user's app.
The core innovation is the use of zero-knowledge proofs (ZKPs). The user's app generates a ZKP, such as a Semaphore proof, that cryptographically attests, 'I have a verified, unique World ID, but I am not revealing which one.' This proof is linked to a nullifier, a unique identifier for that specific action, preventing double-spending of the proof. The user can then present this ZKP, known as a World ID proof of personhood, to any integrated application (dApp) to access services without revealing their identity or linking their actions across different platforms. This process decouples verification from authentication.
On the backend, the protocol's state is managed by a set of smart contracts on the Ethereum blockchain, with Optimism serving as the primary scaling layer for proof verification. The World ID state bridge synchronizes the verified identity commitments (hashes of the user's identity secret) across these chains. When a user performs an action, the dApp's smart contract verifies the ZKP against the current identity tree root, a Merkle root representing all registered identities, ensuring the proof is valid and the nullifier hasn't been used before for that specific action (nullifier hash check).
This architecture enables key properties: Sybil-resistance through biometric uniqueness, privacy through zero-knowledge cryptography, and decentralization through blockchain-based verification. For developers, integration is facilitated by the World ID Software Development Kit (SDK), which provides tools to embed a 'Sign in with World ID' button and verify proofs in their applications. A common use case is sybil-resistant airdrops or governance, where projects can distribute tokens or voting power to unique individuals without collecting personal data.
key-features
WORLD ID
Key Features
World ID is a privacy-preserving digital identity protocol that uses zero-knowledge proofs to verify a user's unique personhood without revealing personal data. Its core features enable global, sybil-resistant authentication.
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World ID & World App
World ID is the private credential stored in a user's wallet (like the World App). The World App is the wallet interface that manages this credential and allows users to generate zero-knowledge proofs for applications. The ID itself is an IrisHash, a unique code derived from biometrics.
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Orb & Biometric Verification
The Orb is a physical imaging device that captures a user's iris pattern to establish uniqueness. This biometric is converted into an IrisHash, which is checked against a global database to prevent double-registration. The raw biometric data is immediately deleted; only the irreversible hash is stored.
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On-Chain & Off-Chain Verification
World ID verification can be used in two primary ways:
- On-Chain: For smart contracts and dApps (e.g., sybil-resistant airdrops, governance).
- Off-Chain: For traditional web2 applications and services (e.g., unique user sign-ups, social media). Both methods use the same underlying ZKP protocol.
core-components
WORLD ID
Core Components
World ID is a decentralized identity protocol that uses zero-knowledge proofs to verify human uniqueness while preserving privacy. It is the foundational identity layer for the Worldcoin ecosystem.
01
World ID (Digital Passport)
A privacy-preserving digital identity that proves an individual is a unique human without revealing their personal data. It is represented by a zero-knowledge proof (zk-SNARK) stored in a user's wallet, enabling anonymous verification for applications. This is the core credential of the protocol.
02
World App (Wallet & Verifier)
The official, privacy-first wallet application that allows users to claim and manage their World ID. It acts as the interface for orb verification, stores the user's zk-SNARK credentials, and facilitates gasless transactions on the World Chain. It is the primary gateway to the Worldcoin ecosystem.
03
The Orb (Hardware Device)
A custom biometric imaging device used for in-person verification of humanness and uniqueness. The Orb captures images of a person's iris, generates a unique IrisHash, and then permanently deletes the original images. This process creates an unforgeable proof of personhood.
04
IrisHash & Uniqueness
A one-way cryptographic hash derived from the biometric patterns of a user's iris. The system compares new IrisHashes against a global database to prevent duplicate registrations, ensuring sybil-resistance. The original biometric data is never stored, only the irreversible hash.
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Semaphore Protocol
The underlying zero-knowledge proof framework that World ID is built upon. Semaphore allows users to prove membership in a group (e.g., verified humans) and signal anonymously (e.g., cast a vote) without revealing their specific identity. This enables private authentication.
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World Chain (Execution Layer)
A Layer 2 blockchain built on Ethereum and optimized for human-centric applications. It is designed to be the primary network for transactions verified by World ID, offering gas subsidies for verified users and prioritizing real-human activity over bots.
ARCHITECTURAL PARADIGMS
Comparison: World ID vs. Traditional Identity Models
A technical comparison of identity verification architectures based on cryptographic proofs versus centralized credential management.
| Core Feature / Metric | World ID (Proof of Personhood) | Centralized Identity Provider (e.g., OAuth, Social Login) | Self-Sovereign Identity (SSI) / Decentralized Identifiers (DIDs) |
|---|---|---|---|
Underlying Architecture | Decentralized, blockchain-anchored (Optimism) | Centralized server database | Decentralized, user-held credentials (e.g., W3C VCs) |
Privacy Model | Zero-knowledge proofs (ZKPs); no personal data stored | Data aggregation; personal data stored by provider | Selective disclosure; credentials stored in user wallet |
Sybil Resistance Mechanism | Global, unique biometric proof (Worldcoin Orb verification) | Phone/email verification, government ID (KYC) | Issuer attestation; no inherent global uniqueness |
User Control & Portability | Proof is portable; no account lock-in | Vendor lock-in; identity tied to provider | High portability; user controls credential sharing |
Censorship Resistance | High; verification is permissionless | Low; provider can revoke access | Medium; depends on issuer availability and resolver networks |
Verification Cost for Developer | < $0.01 per verification (gas cost) | $0.10 - $2.00+ per verification (API fees) | Variable; often free for basic checks, cost for credential issuance |
Primary Trust Assumption | Trust in the ZKP cryptography and decentralized network | Trust in the central provider's security and policies | Trust in the credential issuers (e.g., governments, universities) |
Recovery Mechanism | Phone number or social recovery via guardians | Centralized account recovery (e.g., reset email) | Social recovery or secure seed phrase backup |
ecosystem-usage
WORLD ID
Ecosystem Usage & Applications
World ID is a privacy-preserving digital identity protocol that uses zero-knowledge proofs to verify an individual's unique personhood. Its core applications focus on Sybil resistance and proof-of-personhood for digital services.
01
Sybil-Resistant Airdrops & Rewards
Projects use World ID to distribute tokens or rewards fairly, ensuring each real human can claim only once. This prevents bots and Sybil attackers from draining community funds.
- Example: Optimism's airdrop for governance token distribution.
- Mechanism: Users generate a zero-knowledge proof (zkProof) of their verified uniqueness without revealing their identity.
02
One-User-One-Vote Governance
Decentralized Autonomous Organizations (DAOs) and governance platforms integrate World ID to implement democratic, Sybil-resistant voting. This ensures voting power is based on unique personhood, not capital or multiple wallets.
- Key Benefit: Mitigates whale dominance and vote-buying attacks.
- Implementation: Often used alongside token-based voting for hybrid governance models.
03
Access Gating for Services
Web2 and Web3 services use World ID to gate access to limited resources, ensuring fair distribution among real users. This is critical for applications with supply constraints or those vulnerable to automated abuse.
- Use Cases: Exclusive content platforms, limited NFT mints, or beta software access.
- Privacy: The service only receives a proof of uniqueness, not personal data.
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The World App & Orb Verification
The World App wallet is the primary interface for managing a World ID. Uniqueness is verified through an in-person biometric scan using a physical device called an Orb.
- Process: The Orb performs liveness detection and iris scanning to create a IrisHash.
- Output: A verified credential stored locally on the user's device, enabling the generation of zkProofs.
05
Zero-Knowledge Proofs (Semaphore)
World ID's privacy is built on Semaphore, a zero-knowledge protocol. It allows users to prove membership in the set of verified humans and signal votes or actions without revealing which specific identity they hold.
- Core Concept: Identity nullifier prevents double-signaling while maintaining anonymity.
- Result: Complete separation between verification and on-chain activity.
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Developer Integration (SDK & Widget)
Developers integrate World ID via a Software Development Kit (SDK) and an embedded verification widget. The process is designed for simplicity, requiring minimal changes to existing authentication flows.
- Steps: 1. Integrate the SDK. 2. Embed the widget. 3. Verify the returned proof of personhood on-chain or off-chain.
- Platforms: Supported for web, mobile, and smart contract applications.
security-considerations
WORLD ID
Security & Privacy Considerations
World ID is a privacy-preserving digital identity protocol that uses zero-knowledge proofs to verify human uniqueness without revealing personal data. Its security model relies on biometric verification, decentralized infrastructure, and cryptographic privacy.
01
Zero-Knowledge Proofs (ZKPs)
The core privacy mechanism of World ID. A user proves they are a unique human who has completed an orb verification without revealing which specific identity they are. This is achieved through a Semaphore-based ZK proof, which allows users to generate a 'proof of personhood' that is cryptographically unlinkable to their biometric data or any previous actions.
02
Iris Code & Biometric Security
During orb verification, a user's iris is scanned to create a unique IrisHash. This hash is a one-way, irreversible cryptographic representation. The raw biometric data is immediately deleted from the Orb device. The system's security depends on the uniqueness and liveness detection of the iris scan to prevent Sybil attacks, ensuring one identity per human.
03
Decentralized Identity & Key Management
A user's World ID is represented by a semaphore identity—a set of cryptographic keys stored locally on their device (e.g., in the World App). The private key never leaves the user's custody. This decentralized model eliminates a central database of identities, shifting security responsibility to the user's device and reducing the risk of large-scale data breaches.
04
Sybil Resistance & Uniqueness
The primary security goal is Sybil resistance: preventing a single entity from creating multiple fake identities. World ID enforces this through:
- Global biometric deduplication: The IrisHash is checked against all previously registered hashes on a secure backend.
- One-person-one-proof: A successful verification yields a single, non-transferable proof of personhood.
- Liveness detection: The Orb confirms the scan is from a live human, not a photo or video.
05
Data Minimization & On-Chain Privacy
The protocol is designed with data minimization. On-chain, only the root of the identity merkle tree and ZK proofs are published. No biometric data, personal information, or even the specific Merkle tree path of a user is revealed publicly. Applications receive only a ZK proof of valid, unique membership, protecting user privacy across different dApps.
06
Trust Assumptions & Attack Vectors
Key security assumptions and potential risks include:
- Orb hardware and operator trust: The initial biometric capture must be secure and honest.
- Secure element in the Orb: Protects the signing key that certifies verification.
- User device security: Loss of the device holding the private key means loss of that World ID.
- Cryptographic primitives: Relies on the security of elliptic curve cryptography, zk-SNARKs, and hash functions.
- Governance of the protocol: Upgrades and changes to the smart contracts and backend systems.
WORLD ID
Common Misconceptions
Clarifying frequent misunderstandings about World ID, the Worldcoin protocol's proof-of-personhood system, its privacy model, and its technological underpinnings.
World ID is not a government-issued identity document or a digital passport. It is a cryptographic proof of unique personhood, often called a proof-of-personhood credential. It uses zero-knowledge proofs to allow a user to verify they are a unique human without revealing any personal biometric data. Its purpose is to distinguish humans from bots and sybils in digital applications, not to serve as a legal form of identification for travel, banking, or government services.
WORLD ID
Technical Deep Dive
A deep dive into the technical architecture, cryptographic primitives, and operational mechanics of World ID, the decentralized identity protocol for verifying human uniqueness.
World ID is a privacy-preserving, decentralized identity protocol that uses zero-knowledge proofs to allow individuals to cryptographically prove their unique personhood without revealing their personal identity. It works by having users download the World App, scan their face with their smartphone to generate a unique IrisHash, and receive a Semaphore-based zero-knowledge proof credential stored locally. This credential, often called a World ID, can be used to anonymously prove 'I am a unique human' to any integrated application, such as a social media platform or governance system, preventing sybil attacks. The core infrastructure is secured by the Worldcoin Orb, a custom biometric imaging device that performs the initial verification to ensure uniqueness.
WORLD ID
Frequently Asked Questions
World ID is a privacy-preserving digital identity protocol. These questions address its core technology, use cases, and how it differs from traditional identity systems.
World ID is a privacy-first, decentralized identity protocol that enables users to prove their unique personhood (proof of personhood) without revealing their personal identity. It works by using a zero-knowledge proof (zk-proof) system. Users verify their uniqueness through an in-person orb verification or a phone scan, which generates a cryptographic commitment stored on the blockchain. From this, they can derive a Semaphore-based zero-knowledge proof for any application, proving they are a unique human without linking their activity across services or exposing their biometric data.
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