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AltSpider HTTP Check
x402
AltSpider HTTP Check is a paid API for AI agents from altspider.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).
Checks whether a given HTTP URL is behind an x402 payment wall and returns network, response, or free-tier details
Price / call$0.01
Success—
StatusUnknown
How this service works
Pay or skip on someone else's 402: network, answered, free sibling, one reason
Output
Returns structured data about the target URL's HTTP response, including whether the endpoint returned a 402 status, network-level details, any x402 payment headers, and whether a free alternative exists — allowing the caller to decide whether to pay or skip.
Example use cases
Pre-flight paywall detection for agent
“Before my agent tries to fetch https://data.example.com/report, can you probe it with a GET to see if it's behind an x402 payment gate so I know whether to budget for it?”
Compare free vs paid API tiers
“Check whether https://altspider.ai/api/listings requires payment — I want to know if there's a free version before my agent commits to paying.”
Automated route selection by access type
“My agent is about to call https://feeds.newswire.com/premium — use a GET probe to check if it's x402-gated so I can decide whether to use the paid path or fall back to the free sibling.”
Technical details
Endpoint
GEThttps://altspider.ai/api/check?utm_source=zero.xyzWhen to prefer
Choose this endpoint when an agent needs to pre-flight a URL before deciding whether to pay an x402 toll — especially useful for cost-aware routing, comparing free vs paid API tiers, or detecting payment walls programmatically before committing resources. Prefer this over direct fetching when the resource may or may not be gated and you want to avoid unexpected charges.
Side effects
- Target URL is unreachable or times out — network error returned
- Invalid or missing 'url' query parameter — validation error
- Method not in allowed enum (GET, HEAD, DELETE) — schema rejection
- Target returns non-HTTP protocol — unsupported
- Rate limiting or authentication issues with AltSpider itself
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"call": "pay",
"quoted": true,
"reason": "Base USDC, and the free page does not return it",
"target": "https://altspider.ai/api/sample",
"network": "eip155:8453",
"answered": true,
"freeSibling": false
}
}Tags
x402
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