Verify Claim

{
  "claim": {
    "citations": [
      {
        "provider": "context",
        "quote": "Paris is the capital and largest city of France.",
        "retrieved_at": "2026-10-10T12:00:00.000Z",
        "title": "Paris",
        "url": "https://en.wikipedia.org/wiki/Paris"
      }
    ],
    "claim_id": "clm_3f9a1c2b4d5e6f70",
    "confidence": 0.92,
    "grounding_required": true,
    "rationale_short": "Claim wholly entailed by cited evidence.",
    "span": {
      "end": 30,
      "start": 0
    },
    "support_score": 0.92,
    "text": "Paris is the capital of France",
    "verdict": "supported"
  },
  "job_id": null,
  "mode": "fast",
  "next_actions": [],
  "receipt": {
    "claim_hashes": [
      "sha256:UGFyaXMgaXMgdGhlIGNhcGl0YWwgb2Yg"
    ],
    "created_at": "2026-10-10T12:00:00.000Z",
    "evidence_urls": [
      "https://en.wikipedia.org/wiki/Paris"
    ],
    "priced_usd": 1,
    "verdicts": [
      "supported"
    ]
  },
  "source": "https://en.wikipedia.org/wiki/Paris",
  "upsell": null,
  "why": "Claim wholly entailed by cited evidence."
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://claim-grounding.prospectintel.workers.dev/v1/verify_claim' \
  -H 'content-type: application/json' \
  --data-raw '{"claim":{"text":"Paris is the capital of France"}}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://claim-grounding.prospectintel.workers.dev/v1/verify_claim' \
  -H 'content-type: application/json' \
  --data-raw '{"claim":{"text":"Paris is the capital of France"}}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

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

// Pays at most $1 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$1" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $1 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fclaim-grounding.prospectintel.workers.dev%2Fv1%2Fverify_claim&method=POST
const res = await pay("https://claim-grounding.prospectintel.workers.dev/v1/verify_claim", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "claim": {
      "text": "Paris is the capital of France"
    }
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $1 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$1"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://claim-grounding.prospectintel.workers.dev/v1/verify_claim",
        json={
            "claim": {
                "text": "Paris is the capital of France",
            },
        },
    )
    print(res.status_code, res.text)