What is block explorer?

A website that lets anyone look up transactions, addresses, and blocks on a public blockchain.

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In this entry

A website that lets anyone look up transactions, addresses, and blocks on a public blockchain.

Explorers are how you check that a withdrawal actually left an exchange and how many confirmations it has. Each chain has its own explorers, so a transaction on one chain will not appear on another chain's explorer.

An explorer is a reader, not an authority. It shows you what the chain says, formatted for humans. It cannot change anything, cannot recover anything, and does not hold your funds, which is worth remembering when a support channel points you at one.

How it works

An explorer runs or rents access to a node, often an archive node, and copies the chain's data into a searchable database as new blocks arrive. That indexing step is what makes an address page load instantly instead of scanning the whole chain.

Search accepts three kinds of input. A transaction id shows one transfer and its status. An address shows balance and history. A block height or block hash shows everything included in that block.

Where a contract has been verified, the explorer holds its source and abi, which is what turns raw calldata into readable function names and turns an event log into a labeled transfer line. Unverified contracts show bytes.

Explorers add their own layers that are not chain data: token price estimates, labels naming exchange wallets, spam filters, and scam warnings. These are the operator's judgment, sometimes wrong, and not part of the blockchain.

Most run a public interface for free and sell an application programming interface to developers, which is where the rate limits on heavy lookups come from.

Example

Illustrative: an exchange withdrawal has been pending for 40 minutes. You copy the transaction identifier from the exchange, paste it into the explorer for that chain, and see it confirmed 35 minutes ago with 18 confirmations. That tells you the exchange has done its part and the delay is on the receiving side. If instead the identifier is not found, the exchange has not broadcast it yet, which is a different problem with a different support answer.

Why it matters when you buy

The first time a withdrawal is slow, an explorer is the difference between waiting anxiously and knowing exactly where the funds are. It is also how you check a token contract before buying anything you found through a chart or a social post. See the guide on using a block explorer and the guide on verifying a token contract.

  • transaction id — what you paste into the search box
  • confirmation — the count an explorer displays
  • address — the page showing balance and history
  • abi — what makes a contract call readable
  • archive node — the data source behind historical queries
  • event log — the records explorers turn into transfer lines

Questions

Can an explorer reverse or cancel a transaction?

No. It is a read-only view of data the network already accepted. Nobody operating an explorer can move, freeze, or refund anything.

Why does my transaction not appear?

Either it has not been broadcast yet, or you are searching on the wrong chain's explorer. Both are common, and the second is more likely if the identifier format looks valid.

Are explorer token prices reliable?

Treat them as estimates. They come from whichever market source the operator uses, which can be a single thin pool, so they can differ sharply from the price on a major venue.

Guides that use this term

  • Address Poisoning and Clipboard Attacks: How They Work and How to Avoid Them

    Address poisoning and clipboard hijacking both attack the same habit, which is copying a destination address from somewhere convenient instead of from the recipient, and both are defeated by verifying the full address at the moment you send rather than recognizing the first and last few characters.

  • Crypto Estate Planning: Making Sure Your Coins Aren't Lost With You

    Passing on cryptocurrency requires two things that an ordinary will does not provide on its own, a record of what exists and where, and a route by which the person inheriting it can reach the keys, because no court order can recover a seed phrase nobody wrote down.

  • Gas Fees Explained: Why They Change and How to Pay Less

    A gas fee is the amount of computational work your transaction uses multiplied by the price you pay per unit of that work, and it changes minute to minute because the price rises automatically when blocks are fuller than the network's target.

  • How to Use a Block Explorer to Check a Transaction

    A block explorer is a public search engine for a blockchain, and you check a transaction by pasting its hash into the search box and reading three fields: the status, the number of confirmations, and the receiving address.

  • What Happens If You Lose Your Seed Phrase

    If you lose the seed phrase for a self-custody wallet and no other copy exists, the funds stay visible on the blockchain and become permanently unspendable, because nobody, including the wallet maker, holds a second copy of the key or any authority to reset it.