Base ETH balance API: native balance of any wallet address

$0.01 per call · failed calls are never charged · no account or subscription: pay per call with a card key or USDC

Native ETH balance (eth_getBalance) of any 0x wallet address on Base at the latest block, in wei and in ETH. Use to check whether a wallet can pay gas or a transfer; for ERC-20 tokens use base_token_balance, for all holdings at once use wallet_portfolio. A malformed address is rejected with 400, uncharged.

When to use it

Run it free (25 free calls) Buy credits by card (from $1) Example result (JSON)

Try it with your own inputs

0x wallet or contract address

Uses one of your 25 free calls. Nothing is charged, and a call that fails is not counted.

Inputs

NameTypeDescription
address (required)string0x wallet or contract address

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://tools.funwords.eu/base/balance?address=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"

Or one of your 25 free calls, no key:

curl "https://tools.funwords.eu/base/balance?address=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "chain": "Base",
  "chainId": 8453,
  "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "balanceWei": "1234500000000000000",
  "balance": "1.2345",
  "symbol": "ETH",
  "block": 123456789
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is base_balance, and the first 25 successful calls are free:

https://tools.funwords.eu/mcp

Questions

Does it include tokens?

No, native ETH only (eth_getBalance); base_token_balance reads ERC-20 tokens and wallet_portfolio lists all holdings.

What about a bad address?

A malformed address is rejected with 400 and not charged.

How do I pay?

Each successful call costs $0.01; failed calls are not charged. The first 25 calls are free. Then pay with card credits (from $1; the key goes in an Authorization header or, for clients that can only fetch a URL, as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.

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