ToolVet
78trust / 100

Random Choice

by Random Choice in Onchain & crypto

x402 APIPassing, checked 4 h ago

Cryptographically secure random picker for 2-100 JSON choices. Use for low-stakes one-off random or weighted selection, unbiased tie-breaking, and sampling. Returns the selected value and index, request ID, and weight totals for audit logs. $0.001 USDC per paid request. Not for stable assignments, gambling, security tokens, or consequential decisions; outcomes are not provably fair.

POST
https://random.preflightstack.com/random-choice
Price
$0.001
per call in USDC
Uptime
100%
last 30 days
Response time
461 ms
582 ms slowest 5%
Last check
Passed
4 h ago, next any minute now

Run a free test callHow to call it

Reliability

All checks passedSome failedAll failedNot checked

Status and outage history · Atom feed · Watch with other listings

How to call it

POST https://random.preflightstack.com/random-choice

Each call costs $0.001 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://random.preflightstack.com/random-choice
content-type: application/json

{
  "choices": [
    "alpha",
    "beta",
    "gamma"
  ],
  "weights": [
    7,
    2,
    1
  ]
}

Parameters

ParameterTypeRequiredDescription
choicesarray of anyYesJSON-compatible values to choose from, nested no deeper than 32 levels.
weightsarray of numberNoOptional positive finite relative weights. Must contain exactly one value per choice and does not need to total 100. Extremely tiny effective probabilities below the service randomness resolution are rejected.

Example response

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

{
  "choice_count": 3,
  "index": 0,
  "request_id": "rc_example",
  "selected": "alpha",
  "selected_weight": 7,
  "service_hint": {
    "id": "random-choice",
    "suitable_for": [
      "random_selection",
      "weighted_selection",
      "tie_breaking",
      "sampling"
    ]
  },
  "total_weight": 10,
  "weighted": 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 $0.001.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://random.preflightstack.com/random-choice' \
  -H 'content-type: application/json' \
  --data-raw '{"choices":["alpha","beta","gamma"],"weights":[7,2,1]}'

# 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://random.preflightstack.com/random-choice' \
  -H 'content-type: application/json' \
  --data-raw '{"choices":["alpha","beta","gamma"],"weights":[7,2,1]}' \
  | 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 $0.001 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.001" });
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 $0.001 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Frandom.preflightstack.com%2Frandom-choice&method=POST
const res = await pay("https://random.preflightstack.com/random-choice", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "choices": [
      "alpha",
      "beta",
      "gamma"
    ],
    "weights": [
      7,
      2,
      1
    ]
  }),
});
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 $0.001 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.001"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://random.preflightstack.com/random-choice",
        json={
            "choices": [
                "alpha",
                "beta",
                "gamma",
            ],
            "weights": [
                7,
                2,
                1,
            ],
        },
    )
    print(res.status_code, res.text)

Security scan

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