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OpenVerbs Preflight x402 Inspector
x402
OpenVerbs Preflight x402 Inspector is a paid API for AI agents from preflight.openverbs.com, paid per call via x402, $0.006/call, status unknown (last checked 2026-09-15).
Fetches any public URL and decodes its HTTP 402 Payment Required challenge, returning price, asset, network, payTo, resource, and payment metadata — for free, before committing to payment.
Price / call$0.006
Success—
StatusUnknown
How this service works
Fetch any URL and, without paying, decode its x402 402 Payment Required challenge: price (atomic and formatted for known stablecoins), asset, network, payTo, resource, description, timeout and any input schema. Flags MPP and Bazaar discovery extensions. Returns free:true when no payment is needed. SSRF-hardened: public hosts only; private, loopback, link-local and cloud-metadata addresses are rejected.
Output
Returns a JSON object containing: price in atomic units and formatted for known stablecoins, asset type, network, payTo address, resource URI, human-readable description, timeout duration, optional input schema, boolean flags for MPP and Bazaar discovery extensions, and a free:true flag when no payment is required. SSRF-hardened — rejects private, loopback, link-local, and cloud-metadata addresses.
Example use cases
Preview x402 cost before paying
“Can you check https://data.someservice.io/report and tell me what it costs in USDC and which network I'd need to pay on before I commit to anything?”
Verify free access on x402 resource
“I think this endpoint might be free — can you inspect https://api.opendata.org/feed and confirm whether it returns free:true or if there's a payment required?”
Discover payment terms for agent automation
“I'm building an automation that uses https://market.example.com/prices — can you decode its x402 payment challenge so I know the asset, price, timeout, and any input schema before I wire up the payment logic?”
Technical details
Endpoint
POSThttps://preflight.openverbs.com/v1/inspectWhen to prefer
Use this endpoint when you need to discover and decode the payment requirements of an x402-protected resource before deciding whether to pay. It is the right choice when you want to inspect price, asset, network, payTo address, and timeout without spending any funds. Prefer this over attempting a direct paid request when you want to preview costs, validate payment parameters, or check if a resource is actually free before committing funds in an agentic payment workflow.
Side effects
- SSRF rejection: private/loopback/link-local/cloud-metadata URLs are blocked and return an error
- Non-x402 URLs: if the target does not return a 402 status, the response may indicate no payment challenge found
- Malformed URL: missing or invalid URI format returns validation error
- Timeout: target server slow to respond may cause request to fail
- Non-public hosts: internal hostnames or private IP ranges rejected
- Invalid input schema: missing required fields returns 422 or similar validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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