Latest block number

The latest block number on Ethereum, Base, Polygon, Arbitrum, or Optimism: returns network, blockNumber (integer) and hex. Send GET /api/block-number with no required fields (1 optional) and pay $0.001 per call over x402 or MPP (there is no free tier). It returns a JSON object with network, blockNumber and hex.

The cheapest possible on-chain read - the hello world of paid chain access. For block number plus chain id and gas price in one call use chain-info. Keyless multi-endpoint failover. ?network=base

Category: Crypto & onchain data · Tags: crypto block number latest height rpc evm chain · Also found as: eth_blocknumber

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Parameters

Example request

curl -i "https://agent402.tools/api/block-number?network=base"

Without payment this returns HTTP 402 Payment Required with the exact price for block-number; any x402 v2 or MPP client pays it and retries.

Example response

{
  "network": "base",
  "blockNumber": 27000000,
  "hex": "0x19bfcc0"
}

From an MCP client

catalog.call {
  "slug": "block-number",
  "params": {
    "network": "base"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for block-number; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. Local install: npx -y agent402-mcp.

Errors and behavior

• Every field is optional. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• A POST with a JSON body to /api/block-number is served as this GET, with the body as the input.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/block-number?network=base");

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