Code Size Checker
Free to download on every platform. Comes pre-installed on BotFone, BotPad and BotFlip — with extra free apps included.
About this app
WHAT IT DOES
Code Size Checker lets you check the runtime bytecode size of any deployed smart contract. You provide the contract address, and the tool queries the chain to read the contract's code and calculates its size in bytes. It then compares the size against the EIP-170 limit (24,576 bytes) and displays the result with a visual progress bar. The tool also shows a preview of the bytecode and indicates whether the contract is under the limit, near the limit (>85%), or exceeding it. This is essential for developers deploying contracts on mainnet, where exceeding the code size limit will cause deployment to fail. It reads the current network chain ID from your wallet provider to ensure queries are directed to the correct chain.
HOW TO USE
Connect your wallet using the "Connect" button (required for RPC access). Select the target network (Ethereum Mainnet, Sepolia, Polygon, BSC, Arbitrum, Optimism, and testnets are supported). Enter the deployed contract address. Click "Check code size" — the tool will read the bytecode from the chain and display the size, utilization percentage, and status. The entire operation is read-only — no transactions are signed or sent.
TECHNICAL MECHANISM
The tool uses provider.getCode(address) from ethers.js to fetch the runtime bytecode of the contract. This returns a hex string (0x-prefixed) representing the compiled bytecode. The tool calculates the size by taking the length of the string minus 2 (for the '0x' prefix) and dividing by 2 (since each byte is two hex characters). It then compares this size to the EIP-170 limit of 24,576 bytes (24KB). The result is displayed with a color-coded status badge: green (under limit), yellow (near limit >85%), red (exceeds limit), or gray (no code deployed). The tool also shows a preview of the first 100 bytes of the bytecode for reference. All calls are view functions — no state is modified.
WHAT IT CANNOT SEE
The tool cannot verify if the bytecode is valid or will execute correctly. It cannot detect if the contract is deployed or if the address contains code — it will return a size of 0 for empty addresses. It cannot analyze the bytecode structure or identify optimization opportunities. It is limited by RPC provider availability. It cannot check code size of contracts that are not deployed on the current chain. It cannot check the bytecode of contracts that are being deployed (pre-deployment). It cannot detect if the contract uses proxy patterns where the runtime code is stored elsewhere.
PLEASE NOTE
This tool is for educational and analytical purposes. Always check your contract's code size before deployment to avoid failed deployments due to size limits. The tool does not persist any data; all state is lost on page reload. EVM chains only.
Similar Apps
