An application enabling a user to view details of blocks on a given blockchain. Also known as a blockchain browser.
Block explorers connect directly to a specific blockchain, such as Bitcoin or Ethereum. They allow the user to view and query individual blocks — providing visibility to anyone of the transactions or other actions made by holders of individual cryptocurrencies.
Block explorers are a key part of cryptocurrency's mission of transparency and decentralization, and the universal visibility of all transaction data is one of the key differentiations between cryptocurrency and conventional currencies.
There are a wide range of block explorers available online, with the most popular including Mempool, Bitaps, Blockstream, Multihash, Blockchain Info, and Bitupper Explorer.
Most include the same or similar information at a glance, focusing on the last blocks that have been added to the blockchain, and the blocks that are about to be added next.
Within each block, information is given on block height, the age of the block, the block reward, the identity of the user or pool of users who mined the block, the TX (or transaction list) showing the number of transactions in the block, and the transaction status — that is, whether a transaction is pending or confirmed.
In order to explore specific blocks or transactions, the user of a block explorer must input a specific query. Most commonly this will be the TXID, or transaction hash — a hex sequence used to uniquely identify a specific transaction.
While there are many block explorers on offer, relatively few of them support SegWit, the upgrade to the Bitcoin blockchain activated in 2017. SegWit-enabled block explorers include Bitaps, Apirone, Blockchair, Bitupper, Cryptoid Chainz, and Poolin Explorer.