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X402 Response Header Shape Validator
x402
X402 Response Header Shape Validator is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-19).
Validates an x402 payment-response header for correct base64 or JSON shape, returning acceptance/rejection status with mismatch reasons and normalized evidence
Price / call$0.001
Success—
StatusUnknown
How this service works
X402 Response Header Shape: X402 Response Header Shape checks a payment-response header for bounded base64 or JSON shape from bounded caller-supplied values without an external provider. Call X402 Response Header Shape 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 Response Header Shape as version…
Output
Returns a structured validation result including: explicit acceptance or rejection status, contract-specific check outcomes, normalized evidence extracted from the header, and a list of mismatch reasons explaining any shape violations found in the base64 or JSON header value
Example use cases
Verify x402 header before paying
“I just got an x402 response header back from an agent service — can you run it through shape validation before I authorize payment? The header is: 'eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJhbW91bnQiOiIxLjAwIn0.abc123'”
Detect malformed agent delivery header
“This agent delivery came back with a response header I'm not sure about — can you check if it's a valid x402 shape and tell me the reasons if it gets rejected? Header value: 'eyJ0eXBlIjoiYWdlbnQiLCJzdGF0dXMiOiJjb21wbGV0ZSJ9'”
Pre-acceptance header compliance check
“Before my system accepts this x402 challenge result, validate that the header has the right base64 or JSON shape and give me the normalized evidence and any mismatch reasons: 'eyJjaGFsbGVuZ2UiOiJhYmMiLCJyZXN1bHQiOiJwYXNzIn0='”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/x402-response-header-shape?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a lightweight, no-external-dependency check of an x402 payment or agent delivery response header's structural shape before committing to payment or acceptance. Prefer this over full protocol validators when you only need shape/encoding compliance (base64 or JSON) and want explicit accept/reject status with mismatch reasons — especially useful in agent pipelines where caller-supplied headers must be validated in memory without retention or side effects.
Side effects
- Header exceeds 8192 character limit — request rejected
- Header is neither valid base64 nor valid JSON — rejection with mismatch reason returned
- Malformed input with unparseable structure — explicit rejection status with evidence
- Empty or missing header field — validation fails with descriptive mismatch reason
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| header | string | Header supplied to X402 Response Header Shape; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"encoding": "base64_json",
"shape_valid": true
},
"schema": "delx/util-x402-response-header-shape/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "568768ddc248cedc248ab1ccfdcc4bd01ee9005aa08eff63b5e7df553e7ff724",
"external_calls": 0
},
"operation": "delivery_contract:x402_response_header_shape"
}
}Tags
x402
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