✅ Master ABI Encoding & Decoding

Build dApps that seamlessly interact with any smart contract

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🎓 Key Takeaways

Congratulations! You now understand how to decode blockchain transaction data. Here's what you've mastered:

🔍

You learned what ABIs are, why they're essential, and how they bridge human-readable contracts with machine-executable bytecode.

⚙️

You mastered function selectors, parameter encoding, and how to transform raw hex data into meaningful information.

🔬

You explored how block explorers, wallets, and analytics platforms use ABI decoding to power their services.

🚀

You learned to handle errors, multicalls, custom types, and proxy patterns used in production systems.

Function Selector:

First 4 bytes (8 hex chars) identify the function

Parameter Size:

Each parameter padded to 32 bytes (64 hex chars)

Event Topic[0]:

Keccak256 hash of event signature

Error Selector:

0x08c379a0 for Error(string)

Tools:

ethers.js, viem, web3.py, 4byte.directory

Test your understanding of ABI decoding:

1. What is the function selector for transfer(address,uint256)?

2. How many bytes does each parameter take in encoded calldata?

3. What identifies a specific event in blockchain logs?

4. Which error format is most gas-efficient?

5. What must you verify before decoding transaction data?