On-Chain Credential Verifier

WHAT IT DOES

On-Chain Credential Verifier takes a credential contract address and either a credential ID or a holder address, and provides a complete, plain‑language verification report of the credential's state. On-chain credentials represent verified claims, achievements, memberships, or attestations—often issued by a trusted entity and stored as NFTs or in dedicated credential contracts. If the credential is revoked, expired, or invalid, it should not be relied upon. This tool reads the contract's state via public view functions—hasCredential, getCredentials, isValid, isRevoked, expiry, issuer, metadata, name, symbol, ownerOf, and balanceOf. It fetches the current block timestamp and computes whether the credential has expired (if time‑bound). Historical credential events (CredentialIssued, CredentialRevoked, CredentialVerified, CredentialExpired) are fetched using chunked, backoff‑aware log scanning to provide context on past changes. The output includes the holder, issuer, credential metadata, validity status, revocation status, expiry date and time remaining, a status badge (Valid, Revoked, Expired, Invalid, or Does Not Exist), and a plain‑language verification report explaining whether the credential is currently valid and usable.

HOW TO USE

Enter the credential contract address followed by a colon and either the credential ID (a number) or the holder address to check (e.g., 0x123...:5 or 0x123...:0x456...), select the network, and click "Verify credential". The tool connects to your wallet via the EVM bridge (read‑only; it never signs or sends anything) to fetch the credential state. It attempts multiple common credential function signatures to maximize compatibility with different implementations (ERC‑721, ERC‑1155, and custom credential standards). It fetches the current block timestamp for expiry calculations. Historical events are fetched in chunks (500 blocks per request) with automatic backoff and halving on failure to avoid public RPC caps. The AI layer generates a plain‑English verification report, including whether the credential is sufficient for a transaction. You can click on the contract, holder, or issuer addresses to view them on the block explorer.

CHUNKED LOG SCANNING WITH BACKOFF FOR CREDENTIAL EVENTS

Credential events (CredentialIssued, CredentialRevoked, CredentialVerified, CredentialExpired) are essential for confirming credential history, revocations, and expiry. However, public RPCs aggressively cap eth_getLogs block ranges; a full‑range request over 10,000 blocks will fail with a "block range too large" error. This tool automatically chunks log requests into 500‑block slices to stay within safe limits for all major RPC providers. If a chunk fails (due to timeout or provider‑specific caps), it halves that chunk and retries recursively—ensuring that even with aggressive caps, the tool reliably retrieves all relevant credential events. The tool also filters logs by the specific contract address and relevant event topics to minimize data transfer and processing time. This is essential for detecting revocations and ensuring the credential's current validity status is accurate.

WHAT IT CANNOT SEE

This tool cannot detect credential validity that depends on off‑chain state (e.g., credentials that are verified by an off‑chain attestation service, or credentials that rely on external data sources for validity). It cannot predict future revocations or expiry events that might occur before the transaction is mined—the verification reflects the current state, not the future. It cannot verify that the sender intended to present or interact with the credential—the tool reads what is on‑chain, not the user's intent. It cannot detect risks for credentials that use non‑standard patterns (e.g., custom verification logic not exposed via view functions, or credentials that are bound to external identities). It cannot guarantee that a transaction will succeed even if the credential appears valid, as other conditions (e.g., paused state, expired, or revoked) may also need to be met. It cannot detect if the credential is blacklisted or flagged by external services (e.g., reputation blocklists). It cannot detect if the credential contract is a proxy pointing to an implementation that may have been upgraded with different logic, which could change the behavior of validity or revocation functions. It cannot verify the cryptographic soundness of zero‑knowledge proofs or other advanced verification methods—the tool relies on the contract's view functions to report validity and does not perform cryptographic verification itself. It also cannot detect if the credential's metadata URI points to a valid or accessible off‑chain resource, or if the stored claims have been tampered with off‑chain.

PLEASE NOTE

This tool works only for EVM‑compatible chains (Ethereum, Polygon, BSC, Arbitrum, Optimism, Avalanche, etc.) and relies on standard credential function signatures (hasCredential, getCredentials, isValid, isRevoked, expiry, issuer, metadata, ownerOf, balanceOf). It does not support custom credential logic that does not expose these functions as public view methods. All explanations are AI‑generated from data the app reads on‑chain—the AI synthesizes the credential state, metadata, event history, and transaction context into plain English, but it does not have special access to private contract logic or off‑chain data. Always review what you are actually signing in your wallet before approving any transaction; a credential verification does not replace your own verification of the transaction details, including the target contract, the credential ID, and the function you are calling. This tool is provided free of charge, with no warranty of accuracy or completeness.