ToolVet
78trust / 100

Sats 0 10

by kychange in Onchain & crypto

x402 APIPassing, checked 3 h ago

Swap $0.10 of USDC on Base into sats on Bitcoin Lightning: pay this route over x402, name a Lightning address or a BOLT11 invoice for exactly the quoted sats (or with no amount), and the desk pays the sats within seconds with the preimage as the receipt. Testnet instance: Base Sepolia USDC in, Lightning testnet3 sats out.

POST
https://kychange.com/api/sats/0.10
Price
$0.1
per call in USDC
Uptime
100%
last 30 days
Response time
625 ms
834 ms slowest 5%
Last check
Passed
3 h ago, next any minute now

Run a free test callHow to call it

Reliability

All checks passedSome failedAll failedNot checked

Status and outage history · Atom feed

How to call it

POST https://kychange.com/api/sats/0.10

Each call costs $0.1 in USDC on Base Sepolia, 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://kychange.com/api/sats/0.10
content-type: application/json

{
  "destination": "[email protected]"
}

Parameters

ParameterTypeRequiredDescription
destinationstringYesA Lightning address (name@domain) or a BOLT11 invoice
quote_idstringNoOptional quote_id from GET /api/quote

Example response

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

{
  "sats_out": 995,
  "state": "payout_pending",
  "status_url": "https://kychange.com/api/swaps/swp_…?claim=clm_…",
  "swap_id": "swp_…"
}

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://kychange.com/api/sats/0.10' \
  -H 'content-type: application/json' \
  --data-raw '{"destination":"[email protected]"}'

# 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://kychange.com/api/sats/0.10' \
  -H 'content-type: application/json' \
  --data-raw '{"destination":"[email protected]"}' \
  | 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%2Fkychange.com%2Fapi%2Fsats%2F0.10&method=POST
const res = await pay("https://kychange.com/api/sats/0.10", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "destination": "[email protected]"
  }),
});
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://kychange.com/api/sats/0.10",
        json={
            "destination": "[email protected]",
        },
    )
    print(res.status_code, res.text)

Security scan

1 finding

  • Payment address changed recently in payment
    Payment address changed from 0x58a784f2babd646ba8f5c3c1cd43493cea9feab4 to 0x8acf0d190f77878dcc8531480bfeefd3d6793a73

Recent checks

WhenResultHTTPTimePrice
3 h agoPassed402579 ms$0.1
7 h agoPassed402834 ms$0.1
12 h agoPassed402586 ms$0.1
16 h agoPassed402710 ms$0.1
20 h agoPassed402891 ms$0.1
Show 1 older checks
29 h agoPassed402625 ms$0.1

History

14 Oct 2026Payment address changed from 0x58a784f2babd646ba8f5c3c1cd43493cea9feab4 to 0x8acf0d190f77878dcc8531480bfeefd3d6793a73