Module 9: How to Use a Block Explorer

Key Takeaways

Blockchain search engine: A block explorer is a web tool that lets anyone view and verify data on a public blockchain. It’s like a search engine or browser for the blockchain, indexing every block, transaction, and address for easy lookup.
Search by TX, address, or block: Enter a transaction ID (hash), wallet address, or block number to view details such as sender/recipient, amount, fee, timestamp, and confirmation status.
Chain-specific tools: Each blockchain has its own explorers (e.g., Etherscan for Ethereum, Blockchain.com for Bitcoin). You cannot query Bitcoin data on an Ethereum explorer or vice versa.
Verify and analyze transactions: Explorers help confirm whether a transaction is pending or finalized, and provide network data such as gas fees, latest blocks, and mempool size.
Public data & privacy: Explorer results are fully public and pseudonymous. Never enter private keys, and always verify you are on a trusted site to avoid phishing.

What Is a Block Explorer?

A block explorer (or blockchain explorer) is an online application that allows anyone to browse and search the records stored on a blockchain. It pulls data directly from the public ledger and presents it in a human-readable format. Every block, transaction, and wallet address ever recorded is indexed and can be queried.

Analogy: Think of the blockchain as a massive public library of all transactions. A block explorer is the library’s search catalog: you can look up any “book” by its index (a block or transaction ID) or any “author” by name (an address) and instantly read its contents.

Diagram showing how a block explorer indexes blockchain data

Basic Navigation – Transactions, Addresses, Blocks

Transactions

Paste a transaction hash into the search bar to see its “receipt” on the blockchain: sender, recipient, amount, timestamp, fee, and current confirmation count. This is the fastest way to confirm that your transfer was included in a block.

Addresses (Wallets)

Entering a wallet address shows its current balance and complete transaction history. Many explorers also list any tokens (ERC-20, NFTs, etc.) held by that address. Keep in mind that anyone can view this information – blockchain transparency is a two-edged sword.

Blocks

Searching a block number (height) or block hash displays that block’s miner/validator, timestamp, size, and the list of all transactions it contains. Browsing recent blocks is a good way to see network activity in real time.

Advanced Uses and Tips

Track confirmations: When waiting for a crypto deposit on an exchange, watch the confirmation counter to know when your funds are fully credited.
Monitor network congestion: Many explorers display pending transactions or current gas fees so you can decide whether to wait or pay a higher fee.
Inspect smart contracts: On Ethereum explorers, you can read verified contract code and even interact with “read/write” functions (advanced users only).
Follow wallet activity: Analysts track “whale” wallets to see large transfers. You can also export CSV data for taxes or research.
Use multiple explorers: If one site is slow or offline, try an alternative (e.g., Blockchair for Bitcoin, Ethplorer for Ethereum) to cross-check results.

Risks & Important Considerations

Verify the URL: Phishing sites imitate popular explorers. Check the domain (e.g., etherscan.io, blockchain.com) and ensure the connection is secured (HTTPS).
Read-only by default: Explorers should never ask for your private keys or seed phrase. If a site requests them, leave immediately.
Confirmation depth: Treat transactions as final only after enough confirmations (e.g., six for Bitcoin) to protect against rare chain reorganizations.
Privacy trade-offs: Querying your own address on a public explorer can link your IP to that address in the explorer’s logs. For higher privacy, consider privacy-focused explorers or run your own node.
No fees required: Legitimate explorers are free for basic lookups. If a site charges you just to see a transaction, it’s likely a scam.

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