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B20 Check Token Verification API
x402
B20 Check Token Verification API is a paid API for AI agents from b20check.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).
Returns a signed EIP-712 verdict on issuer powers (mint, freeze, seize, pause, admin) for any B20 token contract on Base
Price / call$0.01
Success—
StatusUnknown
How this service works
Check any B20 token on Base before you trade. A $0.01 API call returns a signed EIP-712 verdict on issuer powers: mint, freeze, seize, pause, admin. Free demo, x402 payments, MCP connector for AI agents.
Output
Returns a JSON object containing: a 'verdict' field (ok/warning/danger), boolean issuer power flags (canMint, canBurn, canPause, canFreeze, canSeize, adminActive), supply cap info, token creation metadata (block, txHash, creator, launcher), historical issuer activity counts (mints, burns, pauses, freezes, seizures), informational flags with severity levels, and a signed EIP-712 attestation object including signer address, issuedAt/expiresAt timestamps, pinnedBlock, attestationId, and signature — allowing on-chain or off-chain verification of the verdict.
Example use cases
Pre-trade token safety check
“I'm about to buy a token at 0xb200000000000000000000f52267Ce6274432c30 on Base — can you verify whether the issuer has any dangerous powers like minting, freezing, or seizing tokens before I put money in?”
DeFi due diligence for new listing
“We're considering listing a new B20 token at address 0xb200000000000000000000f52267Ce6274432c30 on our platform — run a B20 Check on it and tell me if the admin is still active and whether any mint or pause powers are enabled.”
Portfolio risk audit for held tokens
“I hold a bunch of Base tokens and want to know which ones give the issuer power to freeze or seize my balance — can you run a B20 Check on 0xb200000000000000000000f52267Ce6274432c30 and show me the full issuer powers verdict?”
Technical details
Endpoint
GEThttps://b20check.com/v1/verify/%7Baddress%7DWhen to prefer
Choose this endpoint when you need a cryptographically signed, on-chain-verifiable verdict about issuer powers for a specific B20 token on Base — not just a static analysis or heuristic scan. It is the right choice when an agent or user needs an attestation they can present to a third party, when trading or listing decisions require auditability, or when the user wants a single authoritative answer about whether a token issuer can mint, freeze, seize, or pause. Prefer this over generic token scanners when the token is a B20 standard token on Base and you need EIP-712 signed proof rather than an informal risk score.
Side effects
- Invalid or malformed contract address returns an error response
- Address is not a recognized B20 token — isB20 field returns false with no issuer power data
- Payment not received or x402 auth missing — returns 402 Payment Required
- Network congestion on Base may delay response
- Attestation may expire quickly (expiresAt window is short, e.g. 600 seconds) requiring a fresh call
- Token deployed via non-standard launcher may have incomplete creation metadata
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| properties | string |
Output
Schema · Response
{
"type": "json",
"example": {
"flags": [
{
"code": "VIA_LAUNCHER",
"detail": "Created through an intermediary launcher contract, not a direct factory call.",
"severity": "info"
}
],
"isB20": true,
"address": "0xb200000000000000000000f52267Ce6274432c30",
"network": "mainnet",
"variant": "asset",
"verdict": "ok",
"creation": {
"block": 48380900,
"params": {
"name": "Example Token",
"symbol": "EXTKN",
"variant": "asset",
"currency": null,
"decimals": 18
},
"txHash": "0x9a67ce…",
"creator": null,
"launcher": "0x77132d…",
"txOrigin": "0x52c8ff…",
"timestamp": 1783491000,
"viaLauncher": true
},
"attestation": {
"domain": {
"name": "B20 Check Attestation",
"chainId": 8453,
"version": "1",
"verifyingContract": "0xb200000000000000000000f52267Ce6274432c30"
},
"signed": true,
"signer": "0x1388d1e3751512955A53C7c2795Eaf8a3B029e6A",
"issuedAt": 1783670000,
"expiresAt": 1783670600,
"signature": "0x8f2a…",
"pinnedBlock": 48443612,
"attestationId": "0x3e7197…"
},
"issuerPowers": {
"canBurn": false,
"canMint": false,
"canPause": false,
"canSeize": false,
"canFreeze": false,
"supplyCap": "1000000000000000000000000000",
"adminActive": false,
"supplyCapKnown": true,
"freezeConfigured": false,
"transferRestrictions": false
},
"issuerActivity": {
"burns": 0,
"memos": 0,
"mints": 1,
"pauses": 0,
"freezes": 0,
"seizures": 0,
"roleChanges": 0,
"lastActionBlock": 48380900
}
}
}Tags
x402
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