Calc Compound

{
  "annual_rate_percent": 6.5,
  "compounds_per_year": 12,
  "effective_annual_rate_percent": 6.6972,
  "final_balance": 159169.7,
  "interest_earned": 89169.7,
  "method": "monthly stepping with the nominal rate compounded n times per year; contributions added at month end; no tax or inflation",
  "monthly_contribution": 250,
  "principal": 10000,
  "total_contributions": 70000,
  "yearly": [
    {
      "balance": 13760.73,
      "contributions": 13000,
      "interest": 760.73,
      "year": 1
    },
    {
      "balance": 17773.32,
      "contributions": 16000,
      "interest": 1773.32,
      "year": 2
    },
    {
      "balance": 22054.64,
      "contributions": 19000,
      "interest": 3054.64,
      "year": 3
    },
    {
      "balance": 26622.69,
      "contributions": 22000,
      "interest": 4622.69,
      "year": 4
    },
    {
      "balance": 31496.67,
      "contributions": 25000,
      "interest": 6496.67,
      "year": 5
    },
    {
      "balance": 36697.06,
      "contributions": 28000,
      "interest": 8697.06,
      "year": 6
    },
    {
      "balance": 42245.74,
      "contributions": 31000,
      "interest": 11245.74,
      "year": 7
    },
    {
      "balance": 48166.03,
      "contributions": 34000,
      "interest": 14166.03,
      "year": 8
    },
    {
      "balance": 54482.8,
      "contributions": 37000,
      "interest": 17482.8,
      "year": 9
    },
    {
      "balance": 61222.63,
      "contributions": 40000,
      "interest": 21222.63,
      "year": 10
    },
    {
      "balance": 68413.83,
      "contributions": 43000,
      "interest": 25413.83,
      "year": 11
    },
    {
      "balance": 76086.64,
      "contributions": 46000,
      "interest": 30086.64,
      "year": 12
    },
    {
      "balance": 84273.31,
      "contributions": 49000,
      "interest": 35273.31,
      "year": 13
    },
    {
      "balance": 93008.26,
      "contributions": 52000,
      "interest": 41008.26,
      "year": 14
    },
    {
      "balance": 102328.2,
      "contributions": 55000,
      "interest": 47328.2,
      "year": 15
    },
    {
      "balance": 112272.32,
      "contributions": 58000,
      "interest": 54272.32,
      "year": 16
    },
    {
      "balance": 122882.41,
      "contributions": 61000,
      "interest": 61882.41,
      "year": 17
    },
    {
      "balance": 134203.08,
      "contributions": 64000,
      "interest": 70203.08,
      "year": 18
    },
    {
      "balance": 146281.92,
      "contributions": 67000,
      "interest": 79281.92,
      "year": 19
    },
    {
      "balance": 159169.7,
      "contributions": 70000,
      "interest": 89169.7,
      "year": 20
    }
  ],
  "years": 20
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://saylorinnovations.com/api/calc/compound?monthly_contribution=250&principal=10000&rate=6.5&years=20'

# 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/calc/compound?monthly_contribution=250&principal=10000&rate=6.5&years=20' \
  | 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%2Fcalc%2Fcompound
const res = await pay("https://saylorinnovations.com/api/calc/compound?monthly_contribution=250&principal=10000&rate=6.5&years=20");
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/calc/compound?monthly_contribution=250&principal=10000&rate=6.5&years=20")
    print(res.status_code, res.text)