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Pro Messages

by Messages pro in AI models & inference

x402 APIPassing, checked 3 h ago

Anthropic Messages API over x402 - point the Anthropic SDK (or Claude Code / the Agent SDK) at base_url https://agent402.tools/v1/pro and pay $0.10 per call in USDC, no API key, no signup. Same models, caps and price as this tier's /chat/completions route; any model here is served through the Messages wire (Claude natively, others translated). Depth: `effort` (low..max) on Claude 4.7+ and Haiku 5.5, thinking.budget_tokens on older Claude.

POST
https://agent402.tools/v1/pro/messages
Price
$0.1
per call in USDC
Uptime
100%
last 30 days
Response time
201 ms
334 ms slowest 5%
Last check
Passed
3 h ago, next any minute now

Run a free test callHow to call it

Reliability

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Status and outage history · Atom feed · Watch with other listings

How to call it

POST https://agent402.tools/v1/pro/messages

Each call costs $0.1 in USDC on Polygon, paid with the request over x402.

Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.

Example request

From the listing.

POST https://agent402.tools/v1/pro/messages
content-type: application/json

{
  "max_tokens": 256,
  "messages": [
    {
      "content": "Summarize x402 in one sentence.",
      "role": "user"
    }
  ],
  "model": "anthropic/claude-sonnet-5"
}

Parameters

ParameterTypeRequiredDescription
effortstringNo
max_tokensintegerYes
messagesarrayYes
modelstringNo
streambooleanNo
systemstringNo
thinkingobjectNo
toolsarrayNo
zdrbooleanNo

Example response

The provider's example. We can't check it without paying.

{
  "content": [
    {
      "text": "x402 is an HTTP-native way for agents to pay per request with USDC.",
      "type": "text"
    }
  ],
  "id": "msg_…",
  "model": "anthropic/claude-sonnet-5",
  "role": "assistant",
  "stop_reason": "end_turn",
  "type": "message",
  "usage": {
    "input_tokens": 14,
    "output_tokens": 18
  }
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.1.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://agent402.tools/v1/pro/messages' \
  -H 'content-type: application/json' \
  --data-raw '{"max_tokens":256,"messages":[{"content":"Summarize x402 in one sentence.","role":"user"}],"model":"anthropic/claude-sonnet-5"}'

# 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://agent402.tools/v1/pro/messages' \
  -H 'content-type: application/json' \
  --data-raw '{"max_tokens":256,"messages":[{"content":"Summarize x402 in one sentence.","role":"user"}],"model":"anthropic/claude-sonnet-5"}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: pay and call
// 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 $0.1 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.1" });
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 $0.1 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fagent402.tools%2Fv1%2Fpro%2Fmessages&method=POST
const res = await pay("https://agent402.tools/v1/pro/messages", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "max_tokens": 256,
    "messages": [
      {
        "content": "Summarize x402 in one sentence.",
        "role": "user"
      }
    ],
    "model": "anthropic/claude-sonnet-5"
  }),
});
console.log(res.status, await res.text());
Python: pay and call
# 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 $0.1 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.1"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://agent402.tools/v1/pro/messages",
        json={
            "max_tokens": 256,
            "messages": [
                {
                    "content": "Summarize x402 in one sentence.",
                    "role": "user",
                },
            ],
            "model": "anthropic/claude-sonnet-5",
        },
    )
    print(res.status_code, res.text)

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