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CoinOpSelect Proof Hash API
x402
CoinOpSelect Proof Hash API is a paid API for AI agents from coinop.publicvm.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).
Hashes arbitrary text input and returns a hex digest for proof or verification purposes, paid per call via x402 on Base.
Price / call$0.01
Success—
StatusUnknown
How this service works
Paid on-chain token, wallet, contract and research data over x402 on Base.
Output
Returns a JSON object with a 'hash' field containing the hex-encoded hash digest of the input text, and a 'query' field echoing 'proof-hash' as the operation type.
Example use cases
Document fingerprinting for audit trail
“Hash this contract summary text so I have a tamper-evident fingerprint I can store on-chain: 'Parties agree to deliver 500 units by Q3 2025 at a price of $10 per unit.'”
Proof-of-existence for a message
“I want to prove this message existed at a certain time — can you hash it for me: 'User consent recorded for account 0xABC123 on 2025-06-01'?”
Integrity check for research data
“Take this research summary and compute its proof hash so I can verify it hasn't been tampered with later: 'Token XYZ had 1.2M daily active wallets in May 2025 with average tx value of $42.'”
Technical details
Endpoint
GEThttps://coinop.publicvm.com/api/v1/proof/hash?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a simple, paid, on-chain-accountable text hashing service that integrates with the x402 micropayment protocol on Base — especially useful in blockchain agent workflows where proof-of-existence or tamper-evident digests are needed without setting up your own hashing infrastructure.
Side effects
- Input text exceeds 8000 character limit — request rejected
- Missing required 'input' query parameter — returns error
- Payment via x402 not completed or insufficient USDC — 402 Payment Required response
- Invalid method or type parameter — malformed request error
- Network or server unavailability on publicvm.com — connection timeout
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"hash": "hex",
"query": "proof-hash"
}
}Tags
x402
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