Why Most NFT-Based 'Achievement' Systems Fail as Verifiable Credentials

NFTs are permanent, public records. This destroys privacy and creates a permanent liability for the holder.\n- Data is forever: Revocation or updating a credential requires a new NFT, leaving the old, invalid one permanently visible.\n- No selective disclosure: You cannot prove you have a credential without revealing your entire wallet history and all other credentials.

The issuer's smart contract remains the ultimate authority, replicating Web2's walled gardens on-chain.\n- Single point of failure: If the issuer's keys are compromised or the contract has a bug, the entire credential system is invalidated.\n- No user sovereignty: The issuer can often freeze, burn, or alter the properties of the NFT post-issuance, as seen in many gaming and social NFT projects.

Minting an NFT requires capital, not competence. There is no cryptographic link between the credential and the underlying work or identity.\n- Sybil-resistant, not Sybil-proof: Systems like POAP are trivial to farm with multiple wallets, diluting signal.\n- No verifiable link to action: An 'Expert DeFi Trader' NFT cannot cryptographically prove the holder executed profitable trades; it's merely an attestation.

SBTs were marketed as non-transferable proof of identity. In practice, they're just NFTs with a broken transfer function. The issuer can still revoke, censor, or rug the credential, and the holder has no agency.

• No Holder Control: The issuer's key is the single point of failure and control.
• No Selective Disclosure: You can't prove you have a credential without revealing the entire token and its metadata.
• Synthetic Identity Risk: Nothing stops Sybil farming of SBTs from permissionless issuers.

POAPs are the canonical 'I was there' NFT. As a credential, they fail because attestation is binary and context-free. They prove attendance, not competence or reputation.

• No Verifiable Context: A POAP from Devcon doesn't prove you're a developer, just that you bought a ticket.
• Sybil-Flooded: ~10M+ POAPs minted, with low-cost farming trivializing the signal.
• Static & Unverifiable: No mechanism to link a POAP to a subsequent action or skill verification.

Gitcoin Passport aggregates web2 and web3 stamps into a non-transferable, composable score. It succeeds by making Sybil attacks costly and moving beyond binary attestations.

• Costly Sybil: Requires aggregating multiple verified stamps (Google, Twitter, BrightID) to achieve a meaningful score.
• Holder-Centric: Stamps are in the user's custody, though scoring is currently centralized.
• Composable Reputation: The Passport Score is a verifiable, granular metric used by ~500+ projects for sybil-resistant governance and airdrops.

W3C Verifiable Credentials provide the architectural blueprint that on-chain systems ignore. They separate the issuer, holder, and verifier, enabling true user sovereignty.

• Cryptographic Proof: Uses JSON-LD with LD-Signatures or JWT for portable, issuer-independent verification.
• Selective Disclosure: Zero-knowledge proofs (like zk-SNARKs) allow proving a claim without revealing the entire credential.
• Decentralized Identifiers (DIDs): Anchor credentials to a user-controlled DID, not a custodial wallet address.

EAS is a primitive for making any statement on-chain. It succeeds by being schema-agnostic and separating the attestation from the token, focusing on the graph of relationships.

• Schema Flexibility: Anyone can define a data schema for an attestation (e.g., skill, KYC, review).
• On-Chain Graph: Creates a publicly verifiable web of attestations between identifiers.
• Revocation & Delegation: Supports off-chain revocation and delegated attestation flows, moving beyond all-or-nothing models.

The final evolution is ZK-based credential systems like Sismo or zkEmail. They provide maximal privacy and portability by proving claims about off-chain data without revealing it.

• Privacy-Preserving: Prove you're in a DAO's allowlist or have a .edu email without exposing the source.
• Cross-Chain & Off-Chain: The proof is the credential, verifiable anywhere, derived from any data source.
• Composability: ZK proofs of credentials can be inputs for other ZK circuits, enabling complex, private reputation graphs.

An NFT minted by a single private key is a single point of failure. It cannot be programmatically revoked or updated, making it useless for credentials that expire or can be rescinded (e.g., KYC status, professional licenses).

• No Standard Revocation: Relies on off-chain blacklists, breaking the trust model.
• Issuer Risk: Compromised issuer key invalidates all credentials permanently.

An NFT's metadata is a black box. Verifiers cannot cryptographically verify the specific claims or rules behind the achievement without trusting the issuer's off-chain API.

• No ZK-Proofs: Cannot prove you hold a credential without revealing the entire token and your wallet address.
• Siloed Data: Credentials from protocols like Galxe or Layer3 cannot be programmatically composed for complex proofs (e.g., "Prove you have X from A AND Y from B").

The fix is adopting standards like W3C Verifiable Credentials with on-chain attestation registries (e.g., EAS, Verax). This separates the credential from its holder, enabling revocation, selective disclosure via ZK, and trust-minimized verification.

• Sovereign Proofs: Hold credentials in a wallet, prove claims without linking to main address.
• Composable Trust: Build complex attestation graphs that protocols like Uniswap or Aave can query permissionlessly.