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x402 Seller Index

Find cached public x402 endpoints by capability and compare dated unpaid availability, atomic price consistency, correct 402s and matching public Lint metadata.

See a free top-three query

Who it’s for

Agents choosing a public data API and sellers inspecting the available evidence.

Price

Top three matches free. Extended results up to12:0.01 USDC per query; no shared trial. No extra matches means no charge.

Paid calls use x402 with USDC on Base. Read the quote before authorizing payment; examples below do not pay automatically.

Know the limits

Ranks only a bounded nonrandom pool of up to12 fresh cached candidates, not the whole market. Scores stay unknown when history or matching public Lint evidence is missing. All probes are unpaid GET; POST bodies, paid delivery and safety are untested. Tracker context is aggregate only, never a seller-removal claim. No new endpoint fetch, query retention or private monitoring data.

A 30-second integration

Examples use placeholders. Plain requests to paid tools return a payment challenge, not a paid result. Free Lint can perform an unpaid public probe. Inspect the response status and evidence scope before using any result.

curl

curl -i https://api.spendpreflight.com/v1/seller-index \
  -H 'Content-Type: application/json' \
  -d '{"capability":"weather forecast","limit":12}'

MCP

Connect to https://api.spendpreflight.com/mcp. Call the existing tool:

{
  "name": "seller_index",
  "arguments": {
    "capability": "weather forecast",
    "limit": 12
  }
}

SDK / JavaScript

Use standard fetch alongside the SpendPreflight SDK; the example does not invent a dedicated exported method.

// Node.js SDK integration: use your explicitly budgeted fetch.
// Plain fetch below never signs or pays. There is no dedicated
// spendpreflight SDK helper for this operation.
const response = await fetch('https://api.spendpreflight.com/v1/seller-index', {
  method: 'POST', headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({"capability":"weather forecast","limit":12})
});
console.log(response.status, await response.text());

Frequently asked questions

What does a benchmark score mean?

Weights are30 sampled availability,30 current correct402,20 same-asset atomic price consistency and20 public Lint metadata risk. At least two historical samples are required for historical components. The full score is unknown if any component is missing; observed points and a possible range remain visible.

Does my subscription improve my ranking?

No. Subscription status, private monitoring and payer popularity are not joined or used as a ranking boost. Results first enter a bounded pool ordered by latest cached probe and URL, then rank within that pool.

Does this run a new Lint or pay a seller?

No. It reads only previously collected public evidence, and never refreshes, probes, pays, or signs a merchant payment.

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