Latency Budget

{
  "asOf": "2026-10-11T20:19:39.450Z",
  "bottleneck": "app",
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "fanOut": {
    "calls": 100,
    "note": "to have 99% of requests entirely within the per-call latency, each call must meet its target 99.9900% of the time",
    "perCallPercentile": 99,
    "perCallPercentileNeededForSameOverall": 99.98995016917583,
    "probabilityAtLeastOneCallSlowerThanItsPercentile": 0.6339676587267709,
    "requestsHitByTailPercent": 63.3968
  },
  "notChecked": [
    "the distribution of each stage: adding percentiles of stages (p99 + p99) overstates the p99 of the sum, but adding means is exact",
    "queueing delay under load (see /queue-model) and retries",
    "…1 more"
  ],
  "reasons": [
    "Serial stages add; the share column shows where to optimise first.",
    "Tail amplification: with N parallel calls the chance that at least one is slower than its p99 is 1 - 0.99^N (63% for N = 100), so the request is as slow as its slowest call."
  ],
  "serialTotalMs": 240,
  "slackMs": 60,
  "source": "computed locally",
  "stages": [
    {
      "ms": 20,
      "sharePercent": 8.33,
      "stage": "dns"
    },
    {
      "ms": 40,
      "sharePercent": 16.67,
      "stage": "tls"
    }
  ],
  "summary": "Serial total 240 ms; biggest stage app (50%). Within the 300 ms target with 60 ms to spare. Fan-out 100 calls at p99: 63.4% of requests see at least one slow call.",
  "targetMs": 300,
  "targetUsedPercent": 80,
  "verdict": "WITHIN_TARGET"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://data-calc.x402tookit.com/latency-budget?fanOut=100&stages=dns%3A20%2Ctls%3A40%2Capp%3A120%2Cdb%3A60&targetMs=300'

# 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://data-calc.x402tookit.com/latency-budget?fanOut=100&stages=dns%3A20%2Ctls%3A40%2Capp%3A120%2Cdb%3A60&targetMs=300' \
  | 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 $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
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 $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fdata-calc.x402tookit.com%2Flatency-budget
const res = await pay("https://data-calc.x402tookit.com/latency-budget?fanOut=100&stages=dns%3A20%2Ctls%3A40%2Capp%3A120%2Cdb%3A60&targetMs=300");
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 $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://data-calc.x402tookit.com/latency-budget?fanOut=100&stages=dns%3A20%2Ctls%3A40%2Capp%3A120%2Cdb%3A60&targetMs=300")
    print(res.status_code, res.text)