0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001a45524332303a20696e73756666696369656e742062616c616e6365000000000000

✅ Decoded Result

type:

Error(string)

reason:

ERC20: insufficient balance

💡 Key Tips

•Error(string) selector: 0x08c379a0
•Custom errors save gas vs string messages
•Revert reasons are ABI-encoded strings

🔧 Best Practices for Production

✅Always Validate ABI Matches

Before decoding, verify the ABI corresponds to the contract's deployed bytecode. Mismatched ABIs cause incorrect interpretations.

🔄Handle Unknown Functions Gracefully

Not all contracts have public ABIs. Build fallback displays showing raw hex when decoding fails, rather than crashing.

⚡Cache ABIs for Performance

Fetch and cache ABIs to avoid repeated API calls. Popular contracts (ERC20, Uniswap) should be pre-loaded.

🔍Decode Events AND Function Calls

Events often provide more detail than function inputs. A failed transfer might not show why in the input, but the error event will.

🛡️Sanitize Decoded Strings

Malicious contracts can emit invalid UTF-8 or XSS payloads in strings. Always sanitize before displaying to users.

🚀 Advanced Tools & Libraries

ethers.js

Most popular JavaScript library for ABI encoding/decoding with full TypeScript support.

const iface = new ethers.Interface(abi)

viem

Modern, lightweight alternative with better tree-shaking and faster performance.

decodeFunctionData(abi, data)

web3.py

Python library for blockchain interaction with built-in ABI codec.

contract.decode_function_input()

4byte.directory

Database of function selectors to identify unknown contract functions.

GET /api/v1/signatures/?hex_signature=0x...