Grade any x402 seller's payment-security posture from the outside
Grade any x402 seller's payment-security posture from the outside - a read-only black-box check mapped to the 'Five Attacks on x402' failure modes. Probes the URL's 402 challenge (never pays) and scores TLS transport, gated-response cache hygiene (Attack III / cache leakage), error/info-leak hygiene, and payment-terms well-formedness, then returns a letter grade with per-check findings and an honest note on what only insider/active testing can confirm.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
962 msmedian answer time
$0.01listed price per call
$0.01price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
GET https://agent402.tools/api/x402-audit
| Category | Code and developer |
|---|---|
| Provider host | agent402.tools |
| Networks | algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=, eip155:10, eip155:1329, eip155:137, eip155:143, eip155:42161, eip155:42220, eip155:43114, eip155:4663, eip155:8453, solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp, stellar:pubnet |
| Payment schemes | exact, upto |
| Self-reported calls, 30 days | 6 from 2 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.01 | 962 ms |
Example input (from the provider)
{
"method": "GET",
"queryParams": {
"method": "POST",
"url": "https://agent402.tools/api/hash"
},
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"properties": {
"method": {
"description": "HTTP method to probe with (default GET)",
"type": "string"
},
"url": {
"description": "URL of the paid resource to audit",
"type": "string"
}
},
"required": [
"url"
],
"type": "object"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"properties": {
"checks": {
"items": {
"properties": {
"attack": {
"type": "string"
},
"detail": {
"type": "string"
},
"id": {
"type": "string"
},
"severity": {
"type": "string"
},
"status": {
"type": "string"
},
"title": {
"type": "string"
}
},
"type": "object"
},
"type": "array"
},
"grade": {
"type": "string"
},
"paymentRequired": {
"type": "boolean"
},
"reachable": {
"type": "boolean"
},
"score": {
"type": "integer"
},
"status": {
"type": "integer"
},
"summary": {
"type": "string"
},
"url": {
"type": "string"
},
"x402Version": {
"type": "integer"
}
},
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}