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X402 Challenge Version Check
x402
X402 Challenge Version Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).
Validates whether a given x402 challenge protocol version is supported by comparing it against a caller-supplied list of accepted versions, returning acceptance status and mismatch reasons.
Price / call$0.001
Success—
StatusUnknown
How this service works
X402 Challenge Version Check: X402 Challenge Version Check compares challenge protocol version with supported versions from bounded caller-supplied values without an external provider. Call X402 Challenge Version Check before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Challenge Version Check as versi…
Output
Returns an explicit acceptance or rejection status for the given x402 challenge version, along with contract-specific check results, normalized evidence, and detailed mismatch reasons explaining why the version was or was not accepted.
Example use cases
Pre-payment version compatibility gate
“I'm about to pay for an x402 service that sent a challenge with version 4 — check if that's compatible with our supported versions [1, 2, 4] before I authorize anything.”
Agent delivery challenge screening
“We're receiving an agent delivery result packaged with an x402 challenge version of 2. Our system supports versions [2, 3]. Validate whether we should accept or reject it and give me the mismatch reasons if any.”
Multi-version rollout compatibility audit
“I'm rolling out a new x402 integration and need to know if challenge version 7 will be accepted by our current stack that supports versions [5, 6, 7, 8]. Run the version check and show me the normalized evidence.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/x402-challenge-version-checkWhen to prefer
Use this endpoint when an agent or service needs a deterministic, auditable check of whether an incoming x402 challenge version is permissible before proceeding with payment or accepting a delivery. Prefer this over manual in-code comparisons when you need normalized evidence and explicit rejection reasons logged for audit trails, or when building payment-gating workflows where version mismatches must be surfaced clearly.
Side effects
- Version integer outside expected range returns rejection with mismatch details
- supported_versions array exceeds 256-item limit returns validation error
- Missing required version or supported_versions fields returns 400 bad request
- Empty supported_versions list always results in rejection
- Non-integer version values cause schema validation failure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| version | integer | Version supplied to X402 Challenge Version Check; used only for this bounded calculation and processed in memory without retention. |
| supported_versions | array | Supported Versions supplied to X402 Challenge Version Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"version": 2,
"supported": true,
"supported_versions": [
1,
2
]
},
"schema": "delx/util-x402-challenge-version-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "19a97d5b88dfc156ec9b3f1ff4cfb324dd9d18bb96d5ff480a3478193db0eeab",
"external_calls": 0
},
"operation": "delivery_contract:x402_challenge_version_check"
}
}Tags
x402
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