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Delx JSON Contract Check
x402
Delx JSON Contract Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).
Validates a JSON payload against a caller-supplied structural contract and returns path-level validation errors
Price / call$0.002
Success—
StatusUnknown
How this service works
Check a JSON payload against a bounded structural contract and return path-level errors. Use it before an autonomous workflow acts on untrusted input, changes an API, retries a request, or evaluates production reliability. Returns bounded machine-readable JSON for $0.002 USDC via x402 on Base. Execution is deterministic, first-party, local-only, stateless, and does not call an upstream provider; structured validation failures are not billed.
Output
Returns machine-readable JSON containing a list of path-level validation errors found in the instance against the provided contract. Each error identifies the specific JSON path and the nature of the violation (e.g. missing required field, wrong type, value not in enum). If the payload is fully valid, returns an empty errors list. Structured validation failures are not billed.
Example use cases
Validating untrusted webhook payloads
“Before my workflow acts on this incoming webhook, check it against a contract expecting 'orderId' as a required string, 'items' as a required array, and 'total' as a required number — flag any fields that are missing or the wrong type.”
Guarding an API change in production
“I just changed my API response shape and I need to make sure the new payload still satisfies the old contract — the contract requires 'id', 'name', and 'email' as strings; run the check on this new response object and tell me if anything broke.”
Pre-flight check before autonomous retry
“Before my agent retries this failed request, validate the request body against a contract that requires 'action' to be one of 'create', 'update', or 'delete', and 'targetId' to be a required string — return any path-level errors so we know if the payload itself is the problem.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/json-contract-checkWhen to prefer
Choose this endpoint when you need deterministic, stateless, path-level JSON validation against a bounded structural contract — especially in autonomous agent pipelines where you need machine-readable error output before acting on untrusted input, retrying a request, or evaluating API reliability. It is ideal when you control both the contract and the instance, need guaranteed local-only execution with no upstream provider calls, and require that invalid payloads do not incur billing. Prefer it over general-purpose schema validators when operating in a pay-per-call x402 environment and when structured error paths matter more than human-readable messages.
Side effects
- Malformed contract schema causes a contract parse error response
- Instance is not valid JSON, resulting in a parse failure
- Missing 'contract' or 'instance' fields in the request body cause a 400-level error
- Payment of $0.002 USDC via x402 not provided or rejected, blocking execution
- Contract uses unsupported schema keywords beyond type/required/properties/enum, which may be silently ignored or flagged
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| contract | object | Bounded JSON Schema-like contract using type, required, properties, and enum. |
| instance | — | JSON value to check. |
Output
Schema · Response
{
"type": "json",
"example": {
"scope": "bounded structural subset: type, required, properties, enum",
"valid": true,
"errors": [],
"schema": "delx/json-contract-check/v1",
"error_count": 0
}
}Tags
x402
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