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Base Onchain Balance Checker
x402
Base Onchain Balance Checker is a paid API for AI agents from onchaincheck.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).
Returns the native ETH balance and up to 20 ERC-20 token balances for a given Base wallet address, formatted with symbols and decimals.
Price / call$0.005
Success—
StatusUnknown
How this service works
Native ETH balance of a Base wallet plus the balances of up to 20 ERC-20 tokens you list, formatted with each token's symbol and decimals, read live from Base.
Output
A JSON object containing the wallet address, the native ETH balance as a decimal string, and an array of token objects each with the contract address, symbol, decimals, raw integer balance, and human-readable decimal balance. All values are read live from Base at call time.
Example use cases
DeFi portfolio snapshot for a user
“Pull the current ETH balance plus USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) and cbETH (0x2Ae3F1Ec7F1F5012CFEab0185bfc7aa3cf0DEc22) balances for my Base wallet 0x2211d1D0020DAEA8039E46Cf1367962070d77DA9 — show me each with the proper decimals.”
Pre-transaction balance verification
“Before I send a transaction, check whether the Base wallet 0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B has at least 500 USDC — the USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.”
Whale wallet monitoring alert
“Check the live token balances on Base for wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045, including DEGEN (0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed) and Brett (0x532f27101965dd16442E59d40670FaF5eBB142E4), so I can see if they've moved any significant holdings.”
Technical details
Endpoint
GEThttps://onchaincheck.dev/base/balances?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need live, human-readable token balances from the Base network specifically, covering both native ETH and multiple ERC-20s in a single call. It is ideal when you need properly formatted decimals and token symbols without doing your own on-chain RPC calls. Prefer it over generic block explorer APIs when you need structured JSON output for up to 20 tokens simultaneously and are already working within the Base ecosystem.
Side effects
- Invalid wallet address format (non-0x or wrong length) causes a 400 error
- Invalid ERC-20 contract address in the tokens list returns an error or omits that token
- Token contract address is not a valid ERC-20 on Base — may return zero or an error
- More than 20 token addresses provided — rejected by schema validation
- Base network RPC outage causes timeout or 503 response
- Rate limiting or payment failure returns a 402 or 429 response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"chain": "base",
"tokens": [
{
"raw": "3528717773",
"token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"symbol": "USDC",
"balance": "3528.717773",
"decimals": 6
},
{
"raw": "886309838294787826109722",
"token": "0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed",
"symbol": "DEGEN",
"balance": "886309.838294787826109722",
"decimals": 18
}
],
"address": "0x2211d1D0020DAEA8039E46Cf1367962070d77DA9",
"nativeSymbol": "ETH",
"nativeBalance": "7.554675633166555733"
}
}Tags
x402
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