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Mercury · Cited Availability

Monitor$0.005 / callLivex402API key

GET /buy/availability

What it does

URL → a signed uptime/status probe: up/down, HTTP status + class, reachability reason, final URL after redirects, and a measured responseMs — wrapped in an offline-verifiable provenance receipt that makes "it was up/down at T" provable SLA evidence. Deterministic verdict (responseMs is telemetry, not signed). Keyless, no LLM, no signup.

The goal it serves: create provable point-in-time evidence — “it was up / it changed / it answered like this at time T” — for SLAs, change tracking and tamper-evident audit trails.

Schemas & output preview

Input schema — the exact request shape the route validates.

json · input schema

{
  "type": "object",
  "properties": {
    "url": {
      "type": "string",
      "maxLength": 2048,
      "description": "the endpoint/page to probe for availability (http/https)"
    }
  },
  "required": [
    "url"
  ],
  "additionalProperties": false
}

Output schema — the exact response shape the handler returns.

json · output schema

{
  "type": "object",
  "properties": {
    "ok": {
      "type": "boolean",
      "description": "true once the PROBE completed (the host was reached at the network/HTTP layer); false only when the probe itself could not be performed against a reachable host"
    },
    "url": {
      "type": "string",
      "description": "final URL after redirects (or the requested URL when unreachable)"
    },
    "status": {
      "type": [
        "integer",
        "null"
      ],
      "description": "upstream HTTP status observed (null when the host never responded)"
    },
    "text": {
      "type": "string",
      "description": "canonical sorted-key JSON of the signed verdict — the exact string the receipt signs over (responseMs deliberately excluded for determinism)"
    },
    "fetchedAt": {
      "type": "string",
      "description": "ISO-8601 probe time (provenance metadata bound by the receipt)"
    },
    "data": {
      "type": "object",
      "description": "the deterministic availability verdict",
      "properties": {
        "up": {
          "type": "boolean",
          "description": "true iff the host responded with a non-error class (2xx/3xx)"
        },
        "reachable": {
          "type": "boolean",
          "description": "true iff the host produced ANY HTTP response (a 4xx/5xx host is reachable but not up)"
        },
        "httpStatus": {
          "type": [
            "integer",
            "null"
          ],
          "description": "the observed HTTP status, or null when unreachable"
        },
        "responseClass": {
          "type": "string",
          "enum": [
            "1xx-informational",
            "2xx-success",
            "3xx-redirect",
            "4xx-client-error",
            "5xx-server-error",
            "unknown",
            "none"
          ]
        },
        "reason": {
          "type": "string",
          "description": "stable reachability category: ok | <http class> | dns-failure | timeout | connection-refused | connection-reset | tls-error | redirect-loop | blocked-ssrf | invalid-url | unreachable"
        },
        "responseMs": {
          "type": [
            "integer",
            "null"
          ],
          "description": "measured round-trip ms (TELEMETRY — NOT part of the signed text; non-deterministic by nature)"
        },
        "rubric": {
          "type": "string",
          "description": "verdict rubric version id"
        }
      },
      "required": [
        "up",
        "reachable",
        "httpStatus",
        "responseClass",
        "reason",
        "rubric"
      ],
      "additionalProperties": false
    },
    "attestation": {
      "type": "object",
      "description": "EIP-191 provenance receipt over the canonical verdict text — verifiable OFFLINE by anyone (key pinned at /.well-known/mercury-attestation). Proves MERCURY observed THIS up/down + status at THIS time. The SLA-evidence wedge a free uptime checker structurally cannot emit."
    },
    "error": {
      "type": "string",
      "description": "present only when ok:false (the probe could not be performed)"
    }
  },
  "required": [
    "ok",
    "url"
  ],
  "additionalProperties": true
}

Output preview — a real example response, shown free (you only pay when you call the route).

json · output preview

{
  "ok": true,
  "url": "https://example.com/",
  "status": 200,
  "text": "{\"httpStatus\":200,\"reachable\":true,\"reason\":\"ok\",\"responseClass\":\"2xx-success\",\"rubric\":\"mercury-cited-availability-v1\",\"up\":true}",
  "fetchedAt": "2026-06-04T00:00:00.000Z",
  "data": {
    "up": true,
    "reachable": true,
    "httpStatus": 200,
    "responseClass": "2xx-success",
    "reason": "ok",
    "responseMs": 142,
    "rubric": "mercury-cited-availability-v1"
  }
}

Pay & call

Your agent calls the route; the 402 challenge carries the exact price ($0.005, USDC on Base mainnet); the x402 client settles via the CDP facilitator and retries. No key, no signup.

agent.mjs · x402

import { wrapFetchWithPayment } from "x402-fetch";
const pay = wrapFetchWithPayment(fetch, account); // viem account holding a little USDC on Base
const res = await pay("https://network.mercury-hq.com/buy/availability?url=https://example.com");
const out = await res.json(); // the result + `attestation` (the signed receipt)

Prepaid alternative — the same route accepts an API key:

bash · API key

# Same route, prepaid API-key rail (Bearer mk_live_…) — get a key at https://network.mercury-hq.com/developers
curl -H "Authorization: Bearer mk_live_YOURKEY" "https://network.mercury-hq.com/buy/availability?url=https://example.com"

Pay over 402 — get the missing pieceEvery paid call returns an EIP-191 signed receipt — verify it free at /x402/verify.

Verify the receipt

Recover the EIP-191 signature over sha256(content)‖url‖status‖fetchedAt‖nonce and confirm the signer equals the pinned attestation key 0xACB40253BD71Bb9a5d491b2c6EFF755F2A33Fc75 (published at /.well-known/mercury-attestation). No callback to Mercury — the receipt verifies offline, forever. Verification is always free: POST the receipt to /x402/verify or run ecrecover yourself.

Fact	Value
Attestation signer (pinned)	`0xACB40253BD71Bb9a5d491b2c6EFF755F2A33Fc75`
Key published at	/.well-known/mercury-attestation
Live verifier (free)	/x402/verify
Settlement	real USDC on Base mainnet (eip155:8453) via CDP — auditable on BaseScan

Cited Headers

$0.005

URL → a deterministic HTTP security-headers audit (HSTS, CSP, X-Frame, X-Content-Type, Referrer-Policy, Permissions-Policy + more) with a letter…

Open

Cited Redirect