Block explorer

Every explorer is somebody else's full node with a search box bolted on. Bitcoin has produced more than 900,000 blocks since 2009, and an explorer indexes all of them so a lookup returns instantly. The catch is on the other side of the screen: whoever operates it can see exactly which addresses and transactions you asked about.

How it works

An explorer is a full node plus an index that Bitcoin Core does not build for itself.

Core stores blocks and the set of unspent outputs, and with txindex enabled it can also find an arbitrary transaction by its ID. What it deliberately does not keep is a map from addresses to transactions, because maintaining one costs disk and helps nobody who is only spending their own coins. Explorers build that map themselves. Blockstream's Esplora and the software behind mempool.space are both open source, and both exist mainly to answer the question Core will not: show me everything that ever touched this address.

On top of the index sits a view of the mempool, the pool of transactions waiting to be mined. This is the part that differs between sites. Each explorer sees whatever its own node happens to have received, so a transaction can be visible on one and absent from another for several minutes, and a site with an aggressive mempool eviction policy may drop a low fee transaction that another site still shows as pending. Neither is lying. They are reporting different local views of a network that has no single queue.

What an explorer can tell you about one transaction is more than most wallets show. For any transaction ID you get the inputs it spends, the outputs it creates, the total fee in satoshis, the fee rate in satoshis per virtual byte, the size in virtual bytes, whether it signals replaceability, and how many blocks have been mined on top of it. For a block you get the height, the timestamp, the number of transactions, the total fees collected, and usually a guess at which pool mined it. For an address you get its balance and its full history, which is exactly the capability that makes explorers a privacy problem as well as a tool.

The oldest thing worth looking up is block 170, mined on January 12, 2009, which contains the first bitcoin payment from one person to another: 10 BTC from Satoshi Nakamoto to Hal Finney. It renders in a modern explorer like any other transaction, which is a fair demonstration that nothing in the ledger has been rewritten since.

Why this matters when you buy bitcoin

The explorer is how you check that your exchange did what it said it did.

When you withdraw, the exchange gives you a transaction ID. Until that ID appears on the network, the withdrawal has not happened, whatever the account page says about processing. Pasting it into an explorer converts a promise into a fact you can verify yourself, and if the site returns nothing at all, the coins are still with the exchange and the conversation to have is with support, not with your wallet.

It is also how you audit what you were charged. Our exchange reviews list withdrawal fees, and several venues quote a flat figure regardless of network conditions. An explorer shows the fee that was actually paid to miners. When a platform bills a fixed 20,000 satoshi withdrawal fee and the on-chain transaction paid a fraction of that, the difference is the platform's margin, which is legitimate but worth knowing before you choose between a venue with a flat fee and one that passes network cost through.

The privacy cost is real and rarely mentioned. Looking up your own address on a public explorer connects your IP address, and whatever your browser leaks, to that address in someone's server logs. Chain analysis firms buy or operate data sources of exactly this kind. If you hold a meaningful amount, either look up your transactions in a wallet connected to your own node, or run a local copy of mempool.space or Esplora, which the common node bundles package for you.

Finally, the fake explorer is a standard part of the recovery scam playbook. Someone who has already lost coins is shown a convincing looking page displaying a balance that does not exist, then asked for a fee to release it. Two habits defeat it: type explorer addresses yourself rather than following a link, and remember that no explorer can move coins, so no explorer has any reason to ask for a seed phrase, a private key, or a payment. Our guide to avoiding scams covers the wider pattern.

Following an exchange withdrawal, step by step

Take one withdrawal and walk it through an explorer from broadcast to settled.

Copy the transaction ID from your exchange's withdrawal history and paste it into the search box. If the result is not found, wait: the exchange batches withdrawals and may not have broadcast yet. Once it appears, check the outputs first. One of them should be your address and your amount; the other, usually larger, is change returning to the exchange, and its presence is normal rather than a sign that something went wrong.

Then read the fee line. A simple payment with one native segwit input and two outputs occupies about 141 virtual bytes, so at 5 satoshis per virtual byte it pays roughly 705 satoshis in fees. Compare that number against the current mempool bands the explorer displays. If your rate sits above the band clearing the next few blocks, waiting is the correct action. If it sits below everything, the transaction may be pending for a long time, and the explorer will tell you whether it signals replaceability, which decides whether a fee bump is available to whoever sent it.

Confirmations then tick upward, one per block, roughly every ten minutes. One confirmation is enough for ordinary amounts. Six is the convention most exchanges use before crediting a deposit, which is about an hour. After that the transaction ID resolves forever, and it is the receipt you keep for your own records and for a tax return that asks when you acquired the coins.

Block explorer vs node

A block explorer answers questions about the chain; a node decides for itself what the chain is. That difference is the whole point of running one. An explorer shows you what its operator's node believes, and if that node is misconfigured, out of date, or compromised, the page gives you no way to tell. A node you control validates every rule against the blocks themselves, so when your own wallet says a payment arrived, no third party had to be honest for that to be true.

Block explorer vs wallet

A block explorer displays history; a wallet holds keys. An explorer can watch any address on earth and move coins from none of them, which is why the watchlist feature some sites offer is a convenience and never a backup. If a page that looks like an explorer asks you to connect a wallet, enter a recovery phrase, or import a private key to see your balance, it is not an explorer at all.