Arbitrum One recent event logs. Recent contract event logs on Arbitrum One (eth_getLogs): the events a contract emitted over the last N blocks (1-1,000, default 50), optionally filtered by topic0 (the 0x 32-byte event signature hash). Returns up to 100 logs with block, transaction hash and topics. Use to watch transfers or contract events; for one transaction's outcome use arb_receipt.

Token allowance, Arbitrum ERC-20. ERC-20 token allowance on Arbitrum One: how much a spender may move from an owner's wallet (allowance), raw and in token units, and whether the approval is unlimited. Use to check an approval before a swap or to audit risky open approvals; for the owner's balance use arb_token_balance. Token is a ticker (USDC, USDT, WETH…) or a 0x contract; a missing contract is 404 and a non-ERC-20 422, both uncharged.

Eth call, Arbitrum contract call. Read-only contract call on Arbitrum One (eth_call): send ABI-encoded calldata to a contract at the latest block and get the raw return data, without a transaction or gas. Use to read any view function that has no dedicated tool (the example reads USDC totalSupply, selector 0x18160ddd); decode the result with the function's ABI. Calldata up to 8 KB; a call that reverts is 422 with the reason, uncharged.

Arbitrum One ERC-20 token info. Look up the name, symbol, decimals and total supply of an ERC-20 token contract on Arbitrum One, live from the contract. Use to identify an unknown token address or to format raw amounts; for a holder's balance use arb_token_balance. Input is a ticker (USDC, WETH…) or the token's 0x contract address; an address that is not an ERC-20 contract returns 422, uncharged.

Arbitrum One native balance. Native ETH balance (eth_getBalance) of any 0x wallet address on Arbitrum One 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 arb_token_balance, for all holdings at once use wallet_portfolio. A malformed address is rejected with 400, uncharged.

Arbitrum One transaction. Look up an Arbitrum One transaction by hash: sender, recipient, value in ETH, nonce, gas limit, the 4-byte function selector and its block. Use to see what was sent or whether it exists; for success or failure and fees paid use arb_receipt, for emitted events arb_logs. Input is a 0x-prefixed 64-hex hash; an unknown hash returns 404, uncharged.

Base ERC-20 balance. ERC-20 token balance of a wallet on Base (USDC, USDT, WETH or any token, via balanceOf): raw amount, decimals, symbol and the human-readable amount, live from the token contract. Use to check stablecoin or token holdings before a transfer or trade; for the native coin use base_balance. Both inputs are 0x addresses (40 hex characters); no contract returns 404 and a non-ERC-20 contract 422, both uncharged.

Gas history, Base gas price. Gas price history on Base (eth_feeHistory): base fee in gwei for each of the last N blocks (5-100, default 20), how full each block was, and the 10th, 50th and 90th percentile priority fees, with the low, average and high base fee over the window. Use to judge whether fees are rising, pick a priority fee or time a transaction; for the current price alone use base_gas.

Base contract check. Check whether a 0x address on Base is a smart contract or a plain wallet: bytecode size, and whether it is an EIP-1167 minimal proxy and which implementation it points to. Use before sending funds or approving a spender; for a fuller risk verdict use check_counterparty. A malformed address is rejected with 400, uncharged.

NFT owner, Base. Owner of an NFT on Base: the wallet that holds one ERC-721 token id right now (ownerOf), plus the collection's name and symbol. Use to verify who holds an NFT before a trade, a mint gate or an airdrop; for how many a wallet holds use base_nft_balance, for the token's metadata base_nft_metadata. A missing contract is 404, a token that does not exist 422, both uncharged.

Estimate gas, Base. Estimate the gas a transaction would use on Base (eth_estimateGas) and what it would cost at the current gas price, in gas units, gwei and ETH. Give to, plus value in ETH and calldata for a contract call, and the sender when the call depends on it. Use before sending a transaction or to price a batch; for the gas price alone use base_gas. A transaction that would revert is 422 with the reason, uncharged.

Token allowance, Ethereum ERC-20. ERC-20 token allowance on Ethereum: how much a spender may move from an owner's wallet (allowance), raw and in token units, and whether the approval is unlimited. Use to check an approval before a swap or to audit risky open approvals; for the owner's balance use eth_token_balance. Token is a ticker (USDC, USDT, WETH…) or a 0x contract; a missing contract is 404 and a non-ERC-20 422, both uncharged.

Base recent event logs. Recent contract event logs on Base (eth_getLogs): the events a contract emitted over the last N blocks (1-1,000, default 50), optionally filtered by topic0 (the 0x 32-byte event signature hash). Returns up to 100 logs with block, transaction hash and topics. Use to watch transfers or contract events; for one transaction's outcome use base_receipt.

Eth call, Base contract call. Read-only contract call on Base (eth_call): send ABI-encoded calldata to a contract at the latest block and get the raw return data, without a transaction or gas. Use to read any view function that has no dedicated tool (the example reads USDC totalSupply, selector 0x18160ddd); decode the result with the function's ABI. Calldata up to 8 KB; a call that reverts is 422 with the reason, uncharged.

SWIFT code, BIC validation. Check a BIC (SWIFT code) against the ISO 9362 structure: institution code, a real country code with its name, location code, branch code, whether it is the head office (XXX or 8 characters), a test BIC or a passive participant, and the 11-character form. Computed locally; it checks the format and country, not whether the bank exists. Use before an international transfer or to clean payment data; for account numbers use validate_iban.

Storage slot read, Base. Read one raw storage slot of a contract on Base (eth_getStorageAt): the 32-byte word, as a number and, when it holds one, as an address. Slot is a decimal index or a 0x 32-byte key (mapping and proxy slots). Use to inspect contract state that has no getter, owners or implementation pointers; for proxies use base_proxy. A malformed address or slot is rejected with 400, uncharged.

NFT balance, Base. How many NFTs of one ERC-721 collection a wallet holds on Base (balanceOf), with the collection's name and symbol. Use to check a holder before a token-gated action or to see whether a wallet still holds a collection; for who holds one token id use base_nft_owner. Both inputs are 0x addresses; a missing contract is 404, a contract that is not ERC-721 422, both uncharged.

Estimate gas, Ethereum. Estimate the gas a transaction would use on Ethereum (eth_estimateGas) and what it would cost at the current gas price, in gas units, gwei and ETH. Give to, plus value in ETH and calldata for a contract call, and the sender when the call depends on it. Use before sending a transaction or to price a batch; for the gas price alone use eth_gas. A transaction that would revert is 422 with the reason, uncharged.

Eth call, Ethereum contract call. Read-only contract call on Ethereum (eth_call): send ABI-encoded calldata to a contract at the latest block and get the raw return data, without a transaction or gas. Use to read any view function that has no dedicated tool (the example reads USDC totalSupply, selector 0x18160ddd); decode the result with the function's ABI. Calldata up to 8 KB; a call that reverts is 422 with the reason, uncharged.

NFT metadata, Base. NFT metadata on Base: the token URI of one ERC-721 token id (tokenURI) and the JSON it points to (name, description, image, attributes), read from data: URIs, https or ipfs:// (through ipfs.io). Strings over 1,000 characters, such as on-chain SVG images, are shortened. Use to show or check what an NFT is; for its owner use base_nft_owner. A token that does not exist is 422, uncharged; unreachable metadata is reported in metadataError.