75trust / 100

Validity Build

by Validity Transaction Builder in Onchain & crypto

x402 APIPassing, checked 10 min ago

Wrap ANY signed Base transaction (transfer, approve, contract call) in a Cobalt validity transaction: Base holds it dormant until your conditions hold, then includes it — a good-till-block/conditional order, no limit-order contract, nobody holding it. We validate the predicates and return the base_sendRawTransactionValidity request; we never touch funds or keys. Conditions: beforeBlock, fromBlock, flashblockIndex, minNativeBalanceWei, or a storage predicate for price. One required.

GET
https://402.com.tr/api/x402/validity-build
Price
$0.01
per call in USDC
Uptime
100%
last 30 days
Response time
529 ms
709 ms slowest 5%
Last check
Passed
10 min ago, next in 18 min

Run a free test callHow to call it

Reliability

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

How to call it

GET https://402.com.tr/api/x402/validity-build

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.

GET https://402.com.tr/api/x402/validity-build?beforeBlock=40000000&flashblockIndex=0&flashblockIndexOp=%3D&storageOp=%3E%3D

Parameters

ParameterTypeRequiredDescription
balanceAddressstringNoAccount for the balance floor (optional)
beforeBlockstringNoDeadline: before this block (recommended)
flashblockIndexstringNoFlashblock index (optional)
flashblockIndexOpstringNoFlashblock operator (optional, default =)
fromBlockstringNoEarliest block (optional)
minNativeBalanceWeistringNoMin ETH balance floor, wei (optional)
signedTxstringNoYour signed serialized tx (optional)
storageAddressstringNoAdvanced: pool/token for a storage condition
storageMaskstringNoAdvanced: mask (hex, optional)
storageOpstringNoAdvanced: operator (< <= = != > >=)
storageSlotstringNoAdvanced: storage slot (hex)
storageValuestringNoAdvanced: compare value (hex)

Example response

The listing has no example response.

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 'https://402.com.tr/api/x402/validity-build?beforeBlock=40000000&flashblockIndex=0&flashblockIndexOp=%3D&storageOp=%3E%3D'

# 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://402.com.tr/api/x402/validity-build?beforeBlock=40000000&flashblockIndex=0&flashblockIndexOp=%3D&storageOp=%3E%3D' \
  | 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%2F402.com.tr%2Fapi%2Fx402%2Fvalidity-build
const res = await pay("https://402.com.tr/api/x402/validity-build?beforeBlock=40000000&flashblockIndex=0&flashblockIndexOp=%3D&storageOp=%3E%3D");
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.get("https://402.com.tr/api/x402/validity-build?beforeBlock=40000000&flashblockIndex=0&flashblockIndexOp=%3D&storageOp=%3E%3D")
    print(res.status_code, res.text)

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