POSTorigin reachablediscovery only

HTTP Header Checker /check APIPOST /check · x402 API by HTTP Header Checker

Sends a request to a web address you provide and reports back everything the server said in response: the status code, all the response headers, how many times it got redirected, and how long the whole thing took.

https://http-header-checker.underscoredone.com/check

What does this x402 API do?

HTTP Header Checker /check API. This is an x402-gated POST API resource from HTTP Header Checker. TOLL·402 did not invoke this route automatically because doing so was not considered safe. No normalized USD price is recorded; the listing names Base and Solana. No settled paid call has been verified.

Published price
No normalized USD price is recorded
Networks
Base · Solana
Latest evidence
TOLL·402 did not invoke this route automatically because doing so was not considered safe
Resource ID
6677c004ce62c11f06ba0b0d
USE THIS RESOURCE

Start with a quote-only recipe. Payment signing stays in your project.

CODE
AI CODING TOOLS
quote-check.ts
const response = await fetch("https://http-header-checker.underscoredone.com/check", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
  "type": "http",
  "method": "POST",
  "bodyType": "json",
  "bodyFieldNames": [
    "follow_redirects",
    "method",
    "url"
  ],
  "pathParamNames": [],
  "queryParamNames": []
}),
});

console.log(response.status);
console.log(Object.fromEntries(response.headers));
console.log((await response.text()).slice(0, 1000));

// A valid 402 is a quote, not a completed paid call.

Review the provider input schema before running this non-read-only method. No payment code is included.

STATUS HISTORY

  1. Observed in cdp-bazaar

    The registry record was observed and retained with provenance.

  2. Exact route checked

    not safely testable · potentially-mutating-method:POST

  3. Origin reachable

    HEAD https://http-header-checker.underscoredone.com/ returned 301.

What evidence supports this listing?

cdp-bazaarobserved 2026-08-05 · open source record ↗
origin checkHEAD https://http-header-checker.underscoredone.com/ → 301 on 2026-08-05
route quotenot invoked automatically · potentially-mutating-method:POST · 2026-08-05

Each record has an exact-route quote outcome. Unresolved templates and potentially mutating methods are labeled instead of being invoked without provider-specific test input. A quote is still separate from a settled paid call. Read the discovery and verification methodology →

Which networks and payment options does it accept?

The normalized listing price is No normalized USD price is recorded. Raw protocol requirements remain visible below for implementation and audit use.

Baseexact10000 atomic · 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Solanaexact10000 atomic · EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v
HTTP Header Checker POST /check · 6677c0 x402 API · TOLL·402