HTTP headers + security analysis

Fetch a URL and return every response header plus a security analysis: HSTS, CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, COOP/CORP/COEP. Send POST /api/http-headers with the required field url and pay $0.003 per call over x402 or MPP (there is no free tier). It returns a JSON object with url, finalUrl, status, statusText, redirected and 4 more.

Scores 0–100 by presence, flags weak HSTS, and warns on Server/X-Powered-By identity leaks. SSRF-protected.

Category: Network & domains · Tags: security headers audit hsts csp compliance

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/http-headers \
  -H "Content-Type: application/json" \
  -d '{"url":"https://agent402.tools"}'

Without payment this returns HTTP 402 Payment Required with the exact price for http-headers; any x402 v2 or MPP client pays it and retries.

Example response

{
  "url": "https://agent402.tools/",
  "finalUrl": "https://agent402.tools/",
  "status": 200,
  "statusText": "OK",
  "redirected": false,
  "httpVersion": null,
  "headers": {
    "content-type": "text/html; charset=utf-8",
    "server": "railway-hikari",
    "x-content-type-options": "nosniff"
  },
  "security": {
    "score": 100,
    "findings": [
      {
        "header": "HSTS",
        "present": true,
        "value": "max-age=63072000; includeSubDomains; preload"
      },
      {
        "header": "XCTO",
        "present": true,
        "value": "nosniff"
      }
    ],
    "warnings": [
      "info: Server header names the platform (railway-hikari); also visible from DNS, low value to hide"
    ]
  },
  "fetchedAt": "2026-06-19T22:00:00.000Z"
}

From an MCP client

catalog.call {
  "slug": "http-headers",
  "params": {
    "url": "https://agent402.tools"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for http-headers; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. Local install: npx -y agent402-mcp.

Errors and behavior

• url is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• A GET or HEAD to /api/http-headers returns the same 402 quote, so the price can be read without a body.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/http-headers", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "url": "https://agent402.tools"
  }),
});

Part of these workflows

HTTP headers + security analysis is one step in these 11 skill packs, each sold as a single call:

• Security audit - Enumerate a domain's external attack surface in one workflow: certs, DNS posture, email auth, HTTP security headers, and tech stack.
• API investigation - Point at an unknown API endpoint and figure out how to use it: auth scheme, content type, version, rate limits, OpenAPI/Swagger spec discovery, and JSON response structure. The deterministic recon workflow before writing a single line of integration code.
• Convert anything to markdown - Convert anything at a URL - HTML, PDF, or an image - to clean markdown. The 'I have a URL but it might be any content-type, give me markdown either way' workflow: HEAD-detect the content-type, branch to the right deterministic extractor (article extract for HTML, pdf-to-markdown for PDFs, OCR for images), and report token/word stats on the output so the caller can budget the result against an LLM context window.
• Site status snapshot - The 'is this site healthy, addressable, and crawlable - right now?' workflow. DNS resolution → HTTP reachability → security headers → TLS certificate expiry → robots policy. Five tools, one structured status payload an operator (or an uptime bot, or a pre-flight check before an extract/crawl) can act on.
• Technical SEO audit - Can search engines and AI crawlers actually index this page? One pass over reachability, TLS, robots policy, sitemap health, meta/OpenGraph tags, and the on-page link graph.
• Domain intel - Full domain security and SEO intelligence in one call: WHOIS, DNS, TLS cert, HTTP headers, tech stack, robots policy, and certificate transparency.
• SSL audit - TLS/SSL security posture check: live certificate inspection, HTTP security headers, and CAA DNS records.
• Brand protection - Is this domain legitimate? WHOIS age, DNS resolution, scam/phishing search results, and HTTP headers for a quick trust assessment.
• Competitor scan - What's a competitor using? Tech stack, HTTP headers, WHOIS, and page metadata in one call.
• Page audit - Full page SEO + security audit: content extraction, metadata, HTTP headers, robots policy, and sitemap health in one call.
• API health check - Is this API endpoint healthy? Liveness check, response headers, and TLS certificate status in one pass.

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