Tcp Throughput

{
  "asOf": "2026-10-11T14:45:32.620Z",
  "bandwidthMbps": 1000,
  "bdpBytes": 6250000,
  "bdpKiB": 6103.5156,
  "bdpMiB": 5.960464,
  "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.",
  "expectedMbps": 2.861004,
  "limitedBy": "loss",
  "linkUtilizationPercent": 1.0486,
  "mathisLimitMbps": 2.861004,
  "mathisLossPercent": 1,
  "mssBytes": 1460,
  "notChecked": [
    "congestion-control algorithm: the Mathis figure is an upper bound for Reno-style TCP; CUBIC and BBR reach different rates",
    "slow start and short flows",
    "…3 more"
  ],
  "reasons": [
    "Window-limited: window / RTT = 65535 bytes x 8 / 50 ms = 10.4856 Mbps.",
    "Bandwidth-delay product = 1000 Mbps x 50 ms = 6250000 bytes in flight to keep the link full; that needs window scaling with shift 7 (x128).",
    "…1 more"
  ],
  "rttMs": 50,
  "segmentsInFlight": 4280.82,
  "source": "Bandwidth-delay product, RFC 7323 window scaling (max shift 14) and Mathis et al. 1997 (throughput <= (MSS/RTT) x sqrt(3/2) / sqrt(p)), computed locally",
  "summary": "Expected throughput about 2.861004 Mbps, limited by loss; BDP 5.96 MiB.",
  "verdict": "LOSS_LIMITED",
  "windowBytes": 65535,
  "windowLimitedMBps": 1.3107,
  "windowLimitedMbps": 10.4856,
  "windowScaleMultiplier": 128,
  "windowScaleShift": 7,
  "windowToFillLink": 6250000
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://network-calc.x402tookit.com/tcp-throughput?bandwidthMbps=1000&lossPercent=1&mssBytes=1460&rttMs=50&windowBytes=65535'

# 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://network-calc.x402tookit.com/tcp-throughput?bandwidthMbps=1000&lossPercent=1&mssBytes=1460&rttMs=50&windowBytes=65535' \
  | 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%2Fnetwork-calc.x402tookit.com%2Ftcp-throughput
const res = await pay("https://network-calc.x402tookit.com/tcp-throughput?bandwidthMbps=1000&lossPercent=1&mssBytes=1460&rttMs=50&windowBytes=65535");
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://network-calc.x402tookit.com/tcp-throughput?bandwidthMbps=1000&lossPercent=1&mssBytes=1460&rttMs=50&windowBytes=65535")
    print(res.status_code, res.text)