Pay per call with USDC on Base

03 / SEE A REAL 402

The price is in the answer, before you pay

This is what the live API returned to an unpaid request for one location. Amounts are in USDC's six decimal places: 200 means $0.0002. The same call for the county forecast status route returned an amount of 50000, which is $0.05. Check the price on every route yourself before paying.

# Free: ask without paying. You get a 402 and the price, nothing is charged.
curl -i -X POST https://data.truefixr.com/v1/weather/batch \
  -H "content-type: application/json" \
  -d '{"locations":[{"lat":32.78,"lon":-96.80}]}'
# HTTP/2 402
# payment-required: <base64 JSON, decoded on the right>

{
  "x402Version": 2,
  "accepts": [{
    "scheme": "exact",
    "network": "eip155:8453",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "200",
    "payTo": "0xFf23cfFf46535E076e88835CD0Bbad8D1033E255",
    "maxTimeoutSeconds": 300
  }]
}

Verify the pay-to address against /.well-known/x402.json before you fund anything. Both showed the same address when we checked on October 3, 2026.

05 / CODE

Python, with the official x402 client

The script first asks the price with a plain request and pays nothing. Only with --go does it pay. The wallet key comes from X402_PRIVATE_KEY, never from the code.

"""Pay per call with USDC on Base (x402). No account, no API key.

pip install requests "x402[httpx,evm]" eth-account
export X402_PRIVATE_KEY=0x...     # a DEDICATED wallet holding a few dollars of USDC on Base. Never your main wallet.

python x402_pay.py          # dry run: asks the price, pays NOTHING
python x402_pay.py --go     # really pays (about $0.0002 per location for weather)

Structure proven against this API with the official Python x402 v2 client. Other clients are untested.
GetFixn sells data, not trading advice. Forecasts can be wrong.
"""
import asyncio
import base64
import json
import os
import sys

import requests

URL = "https://data.truefixr.com/v1/weather/batch"
BODY = {"locations": [{"lat": 32.78, "lon": -96.80, "label": "Dallas"}]}


def quote():
    """Unpaid request. The server answers 402 and says what it wants. Costs nothing."""
    r = requests.post(URL, json=BODY, timeout=30)
    if r.status_code != 402:
        sys.exit("expected 402, got %s" % r.status_code)
    need = json.loads(base64.b64decode(r.headers["payment-required"]))["accepts"][0]
    usd = int(need["amount"]) / 1_000_000  # USDC has 6 decimals
    print("price: $%.4f USDC on %s, pay to %s" % (usd, need["network"], need["payTo"]))
    return usd


async def pay():
    from eth_account import Account
    from x402 import x402Client
    from x402.http.clients import x402HttpxClient
    from x402.mechanisms.evm import EthAccountSigner
    from x402.mechanisms.evm.exact import register_exact_evm_client

    acct = Account.from_key(os.environ["X402_PRIVATE_KEY"])
    client = x402Client()
    register_exact_evm_client(client, EthAccountSigner(acct))
    async with x402HttpxClient(client) as http:
        r = await http.post(URL, json=BODY)  # 402 -> sign -> retry, all inside the client
        await r.aread()
        print(r.status_code, r.text[:400])


if __name__ == "__main__":
    price = quote()
    if "--go" in sys.argv:
        asyncio.run(pay())
    else:
        print("dry run only. Add --go to pay $%.4f." % price)

pip install requests "x402[httpx,evm]" eth-account
export X402_PRIVATE_KEY=0x...   # dedicated low-balance wallet only
python x402_pay.py        # dry run, pays nothing
python x402_pay.py --go   # pays about $0.0002

07 / WALLET SAFETY

Use a dedicated, low-balance wallet

1. One wallet, one job. Create a new wallet just for this bot. Never use the wallet that holds your savings or other assets.
2. Keep it small. Fund it with a few dollars of USDC on Base, enough for a day or a week. Top it up on purpose.
3. Base network only. Send USDC on Base. Sending the wrong token or network to a wallet can lose the funds.
4. Key in an environment variable. X402_PRIVATE_KEY on your own machine. Not in code, not in git, not in screenshots, not in a chat with an AI model. Put .env in .gitignore.
5. Dry run first. Print the price and exit, as the example does, and only pay when you have said so.
6. Cap spending in your code. A bug in a loop should hit a ceiling, not an empty wallet.
7. Check the pay-to address. It must match the address in /.well-known/x402.json. A mismatch means stop.
8. Leaked key means move funds. If you think the key leaked, move what is left to a new wallet right away and stop using the old one.

GetFixn sells data, not trading advice. Nothing here is investment advice. Forecasts can be wrong. You are responsible for your own strategies and wallets, and for following the rules of any exchange or market you use. Not financial, tax or legal advice about crypto. We have no partnership with or endorsement from any exchange, wallet or chain. Heavy or commercial/trading volume? Email admin@truefixr.com.