A block explorer, also called a blockchain explorer or blockchain browser, is a tool that lets users view and search public data recorded on a blockchain. Most explorers are web-based applications, and many also provide an API so wallets, exchanges, and analytics platforms can query chain data programmatically.
What a block explorer shows
At a basic level, a block explorer helps you inspect blocks and transactions as they are added to the chain, all the way back to the genesis block. You can typically look up a transaction hash to see its status, the fees paid, the sender and recipient addresses, and when it was included in a block. You can also search addresses to view balances and a history of incoming and outgoing transfers.
Explorers often expose more technical details for advanced users, such as confirmations, block height, timestamps, validator or miner information, and smart contract interactions on programmable networks. On account-based chains, explorers may decode contract calls so you can see which function was executed and what parameters were supplied.
How people use block explorers in practice
A common use case is verifying a payment. If you withdraw crypto from an exchange, you can paste the transaction ID into a block explorer to confirm it was broadcast, included in a block, and has the expected number of confirmations. Developers also use explorers to debug dApp behavior by inspecting contract events, token transfers, and failed transactions.