Defi Swap Quote

{
  "advantage_over_next_bps": 0.8,
  "best": "KyberSwap",
  "best_amount_out": 2432.128359,
  "chain": "ethereum",
  "effective_price": 2432.128359,
  "from": {
    "address": "0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
    "amount": 1,
    "symbol": "ETH"
  },
  "note": "Indicative sell quotes before slippage, fees and gas; nothing is signed or executed. Net of gas the better aggregator can differ, so compare usd_out minus gas_usd for small trades.",
  "quotes": [
    {
      "aggregator": "KyberSwap",
      "amount_out": 2432.128359,
      "dexes": [
        "pmm-1/uniswapv3"
      ],
      "gas_usd": 0.12820052466337872,
      "price_impact_note": null,
      "usd_out": 2436.0765781557607
    },
    {
      "aggregator": "Paraswap",
      "amount_out": 2431.940998,
      "dexes": [
        "uniswapv3"
      ],
      "gas_usd": 0.029569,
      "price_impact_note": null,
      "usd_out": 2430.8976953119
    }
  ],
  "source": "Paraswap and KyberSwap aggregator APIs",
  "to": {
    "address": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "symbol": "USDC"
  }
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://saylorinnovations.com/api/defi/swap-quote?amount=1&chain=ethereum&from=ETH&to=USDC'

# 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 - 'https://saylorinnovations.com/api/defi/swap-quote?amount=1&chain=ethereum&from=ETH&to=USDC' \
  | 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 $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
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 $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fsaylorinnovations.com%2Fapi%2Fdefi%2Fswap-quote
const res = await pay("https://saylorinnovations.com/api/defi/swap-quote?amount=1&chain=ethereum&from=ETH&to=USDC");
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 $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://saylorinnovations.com/api/defi/swap-quote?amount=1&chain=ethereum&from=ETH&to=USDC")
    print(res.status_code, res.text)