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VulnHunt Smart Contract Change Detection API
x402
VulnHunt Smart Contract Change Detection API is a paid API for AI agents from vulnhunt-agent-api-production.up.railway.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).
Returns the latest observed state change for a smart contract on a specified chain, including which fields changed, previous and current state, and whether reassessment is required.
Price / call$0.01
Success—
StatusUnknown
How this service works
Read-only historical smart-contract security intelligence for autonomous agents.
Output
Returns a JSON object with a 'change' object describing which fields changed (e.g. 'implementation'), the change status ('changed' or otherwise), the timestamp it was observed, the previous and current on-chain state values, and a boolean indicating whether reassessment is required. Also includes a 'coverage' object with the observation status of this contract.
Example use cases
Proxy upgrade detection for DeFi protocol
“Check if the Aave proxy contract at 0xB53C1a33016B2DC2fF3653530bfF1848a515c8c5 on Ethereum mainnet (chain ID 1) has had its implementation address changed, and tell me if a security reassessment is now required.”
Security audit trigger for DAO treasury
“I need to know if the DAO treasury contract at 0xFE89cc7aBB2C4183683ab71653C4cdc9B02D44b7 on chain 137 has changed state recently — specifically which fields changed and what the before and after values are.”
Automated monitoring alert for changed contract
“Check the latest change record for smart contract 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 on chain ID 1 — has its implementation or any key field been updated, and when was that observed?”
Technical details
Endpoint
GEThttps://vulnhunt-agent-api-production.up.railway.app/v1/contracts/%7Bchain_id%7D/%7Baddress%7D/changeWhen to prefer
Use this endpoint when you need to know specifically whether a smart contract's on-chain state has changed between observations — particularly for proxy upgrade detection, implementation address tracking, or triggering downstream security reassessments. Prefer this over general blockchain explorers when you need structured change-diff data (before/after state) with security-context flags like reassessment_required, rather than raw transaction history.
Side effects
- Contract address not found or not yet observed returns coverage status indicating no data
- Invalid chain_id returns an error
- Malformed contract address returns validation error
- Contract has no recorded changes returns a status indicating no change observed
- Service unavailable returns 5xx error
- Payment not completed (x402) returns 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"change": {
"fields": [
"implementation"
],
"status": "changed",
"observed_at": "2026-01-01T00:00:00Z",
"current_state": {
"implementation": "0x0000000000000000000000000000000000000001"
},
"previous_state": {
"implementation": "0x0000000000000000000000000000000000000000"
},
"reassessment_required": true
},
"coverage": {
"status": "observed"
}
}
}Tags
x402
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