ToolVet
75trust / 100

Compound Interest Calculator

by Sindri in Markets & finance

x402 APIPassing, checked 6 min ago

Compound interest calculator. Projects the ending value of an investment given a starting principal, monthly contributions, and an annual interest rate, compounded monthly over a chosen number of years.

POST https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator

Last 30 days

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Status and outage history · Atom feed

Uptime
100%
Response time
410 ms typical, 569 ms slowest 5%
Last check
6 min ago
Next check
in 22 min

How to call it

POST https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator

Each call costs $0.01 in USDC on Base, 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://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator
content-type: application/json

{
  "annualInterestRate": 0.07,
  "initialInvestment": 10000,
  "monthlyContribution": 200,
  "years": 20
}

Parameters

ParameterTypeRequiredDescription
annualInterestRatenumberYesAnnual interest rate, as a fraction (e.g. 0.07).
initialInvestmentnumberYesStarting principal.
monthlyContributionnumberYesRecurring monthly contribution.
yearsnumberYesNumber of years to project (1-100).

Example response

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

Example response, 36 lines
{
  "data": {
    "endingValue": 144572.72045492515,
    "params": {
      "annualInterestRate": 0.07,
      "initialInvestment": 10000,
      "monthlyContribution": 200,
      "years": 20
    },
    "totalContributions": 58000,
    "totalGrowth": 86572.72045492515,
    "yearlyBalances": [
      13201.41786649044,
      16634.266489404075,
      20315.276016835352,
      24262.386020637212,
      28494.83292576237,
      33033.243759878744,
      37899.736680152215,
      43118.02876711856,
      48713.55161098314,
      54713.57525366362,
      61147.3410906128,
      68046.20438012511,
      75443.78705465242,
      83376.14157886199,
      91881.92665300699,
      101002.5956179077,
      110782.59847974403,
      121269.59853923674,
      132514.70468096953,
      144572.72045492515
    ]
  },
  "ok": true
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.01.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator' \
  -H 'content-type: application/json' \
  --data-raw '{"annualInterestRate":0.07,"initialInvestment":10000,"monthlyContribution":200,"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 - -X POST 'https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator' \
  -H 'content-type: application/json' \
  --data-raw '{"annualInterestRate":0.07,"initialInvestment":10000,"monthlyContribution":200,"years":20}' \
  | 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 $0.01 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%2Fppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws%2FcompoundInterestCalculator&method=POST
const res = await pay("https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "annualInterestRate": 0.07,
    "initialInvestment": 10000,
    "monthlyContribution": 200,
    "years": 20
  }),
});
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 $0.01 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.post(
        "https://ppu43fkyhimq5fiqpmo42eh5ri0yypid.lambda-url.us-east-1.on.aws/compoundInterestCalculator",
        json={
            "annualInterestRate": 0.07,
            "initialInvestment": 10000,
            "monthlyContribution": 200,
            "years": 20,
        },
    )
    print(res.status_code, res.text)

Security scan

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