Contract Call Builder

WHAT IT DOES

Contract Call Builder is a developer tool that lets you construct and execute arbitrary contract calls using a custom ABI. Paste any contract ABI, select a function, fill in the parameters, and the tool encodes the function call data, builds the transaction, and sends it through your wallet. This is essential for interacting with contracts that aren't supported by standard interfaces, testing function calls before integrating them into your own applications, or performing one-off administrative actions on deployed contracts. The tool also supports sending ETH along with the call (payable functions) and works with any EVM-compatible chain.

HOW TO USE

Connect your wallet using the BGWallet bridge (MetaMask or any Web3 wallet). Enter the contract address you want to interact with. Paste the contract's ABI as a JSON array in the text area — this defines the available functions and their parameter types. Enter the function name you want to call. The tool parses the ABI and generates input fields for each parameter based on the function's inputs. Fill in the parameter values — the tool supports basic types including address, uint/int (with any bit size), bool, and string. Optionally set a value in ETH for payable functions, and a gas limit (or leave it empty for auto-estimation). Review the encoded data preview and transaction details, then click "Execute call" to sign and send the transaction through your wallet. Results appear with transaction hash, confirmation status, and gas usage.

TECHNICAL MECHANISM

The tool uses ethers.js to parse the ABI and encode function calls. When you enter an ABI and function name, the tool uses ethers.utils.Interface to parse the ABI JSON and locate the matching function fragment. For each input parameter defined in the ABI, the tool creates an input field and attempts to parse the entered value according to the parameter type — handling address validation, number parsing for uint/int types, boolean conversion, and string passthrough. When you click execute, the tool calls iface.encodeFunctionData(functionName, args) to generate the full calldata (function selector + encoded parameters). It then constructs a transaction object with the contract address, calldata, value (if any), and optional gas limit, and sends it using signer.sendTransaction(). After the transaction mines, the tool reads the receipt and displays the status and gas used (using receipt.gasUsed for actual consumption and receipt.effectiveGasPrice for accurate cost in post-EIP-1559 networks). The entire process is transparent — you can see the raw encoded data before signing.

WHAT IT CANNOT SEE

The tool cannot automatically fetch ABIs from Etherscan, BscScan, or other block explorers — you must paste the ABI manually. It cannot validate that the provided ABI matches the deployed contract at the address you entered — mismatched ABIs will produce invalid calldata that may revert or cause unexpected behavior. It cannot simulate transactions to predict gas usage or whether the call will succeed — you can only know by sending the transaction and waiting for the result. It cannot handle contracts that require complex nested structs, arrays of structs, or multi-dimensional arrays in function parameters beyond basic types. It cannot decode return values from view/pure functions — it only supports state-changing transactions. It cannot interact with contracts that require EIP-712 signatures or other advanced authorization mechanisms. The tool does not verify any contract code.

PLEASE NOTE

This tool works exclusively on EVM-compatible chains (Ethereum, BNB Chain, Polygon, Arbitrum, Optimism, Base, Avalanche C-Chain, Fantom, and others). Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. The ABI must be a valid JSON array in the standard format. Ensure you understand the function you are calling — incorrect parameters may result in failed transactions and lost gas. Always test on testnets before using on mainnet. The tool is provided as-is with no warranty or liability. Review the encoded data before signing any transaction.