What is etherscan & how does it work?

Although mostly known as an Ethereum blockchain explorer, Etherscan also offers a source code verification service for smart contract developers and users. Etherscan allows you to recompile contract bytecode from the original data payload (source code, library address, compiler settings, contract address, etc.)

Is etherscan a good tool for verifying contracts?

Etherscan is the most used tool for verifying contracts. However, Etherscan's contract verification has a drawback: it fails to compare the metadata hash of the on-chain bytecode and recompiled bytecode. Therefore the matches in Etherscan are partial matches. More on verifying contracts on Etherscan.

What is write contract feature in etherscan?

While some of the functions allow you to add input to the contract so that it can call the information related to the input data. In the example below, we queried how much USDT that Etherscan: Donate address has. Write Contract Feature allows you to interact with the contract directly on Etherscan.