What is a block explorer and how to use one? (Etherscan Guide)

What Is a Block Explorer?

1. A block explorer is a web-based tool that allows users to search and verify transactions, addresses, blocks, and other on-chain data in real time.

2. It functions like a public ledger interface—anyone can input a wallet address or transaction hash and retrieve verifiable details about its activity on the blockchain.

3. For Ethereum, Etherscan is the most widely adopted block explorer due to its reliability, rich feature set, and long-standing reputation among developers and traders.

4. Unlike centralized databases, block explorers do not store data themselves—they query nodes connected to the Ethereum network and present results in a human-readable format.

5. Every transaction confirmed on Ethereum appears on Etherscan within seconds, making it indispensable for tracking fund movements, contract interactions, and gas usage.

How to Look Up a Wallet Address

1. Navigate to etherscan.io and locate the search bar at the top center of the homepage.

2. Paste a valid Ethereum address—either an externally owned account (EOA) or a smart contract address—into the field and press Enter.

3. The resulting page displays the address’s balance, total number of transactions, internal operations, token holdings, and associated smart contract code if verified.

4. Users can scroll down to view the transaction history chronologically, with each entry showing timestamp, block number, sender, receiver, value transferred, and gas fee paid.

5. Clicking any transaction hash reveals granular details including input data, status, and decoded logs—especially useful when debugging failed contract calls.

Understanding Transaction Details

1. Each transaction record includes a status indicator: green for success, red for failure, and yellow for pending state.

2. The “Value” field shows ETH transferred; “Txn Fee” reflects the total gas cost calculated as gas used multiplied by gas price.

3. Under “More Info”, users find the “Input Data” section—this contains encoded function calls and parameters sent to smart contracts.

4. If the receiving address is a verified contract, Etherscan attempts to decode the input using ABI metadata, displaying readable function names and arguments.

5. The “Internal Transactions” tab exposes value transfers triggered by contract execution, such as those from decentralized exchanges or yield protocols.

Verifying Smart Contracts

1. Developers deploy contracts on Ethereum and may choose to verify source code on Etherscan to enable transparency and trust.

2. Verified contracts display a green checkmark next to their name and expose tabs for “Contract”, “Read Contract”, and “Write Contract”.

3. The “Read Contract” interface lets anyone call view functions without spending gas—for example, checking token supply or owner address.

4. “Write Contract” requires connection via MetaMask or similar wallet and permits authenticated interaction—like approving token allowances or claiming rewards.

5. Contract creation code, runtime bytecode, and compiler version are all publicly accessible under the “Contract Source Code” tab.

Frequently Asked Questions

Q: Can I use Etherscan to track tokens on networks other than Ethereum?A: Etherscan only supports Ethereum mainnet and select layer-2 chains like Arbitrum One and Optimism. For BNB Chain or Solana, separate explorers like BscScan or Solscan must be used.

Q: Why does my transaction show “Pending” for a long time?A: This typically occurs when gas fees are set too low relative to current network congestion. Etherscan displays the recommended gas price on its homepage to help avoid delays.

Q: Is it safe to connect my wallet to Etherscan’s “Write Contract” feature?A: Yes—as long as you’re on the official etherscan.io domain and never enter your private key. Wallet connections use secure signing protocols and do not grant Etherscan control over funds.

Q: How do I know if a token listed on Etherscan is legitimate?A: Check whether the token’s contract is verified, has sufficient transaction volume, and appears on reputable DEXs. Avoid tokens with no audit links, anonymous teams, or suspicious transfer restrictions.