Block chain browser

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Block Explorer

A Blockchain Explorer is a web application to view and query blocks [1] working as a web browser that is not connected to the internet, like Google Chrome, but to the Blockchain. Their primary function is to allow everyone with an internet connection to track in real-time all the transactions or interactions made by each cryptocurrencies holders, regardless of his or her level of knowledge and expertise. [2]. However, although there are plenty of Explorer available, only a tiny minority are able to show the transaction using SegWit (Bitcoin bech32 addresses start with “bc1”) [3]

The default view

The default view in the main page generally provides in real time information about of all the last blocks that are being added to the blockchain, most often separated into six columns with this following informations:

Block height: [4] block number since the Bitcoin genesis block was mined. Each new mined block assumes an increase of one at the height of the block. Thus, the number 492800 in this column means this is the 492800th block mined in the whole history.

Age: the moment when the block was accepted by a miner and not when the user initiated a payment or transfer to another wallet.

Confirmation: The most relevant information visible at a glance, the transaction status. If a transaction is «unconfirmed» or «pending», that means the transaction is in the Blockchain, but has not included in a block yet. In average, it takes typically 10 minutes for a bitcoin transaction to be confirmed. It will take about one hour to get «confirmed» by six confirmations.

Transaction list (TX): number of transactions included in the block. [5]

Reward: the reward for those (miners) who mined the block.

Mined by: name of the miner who mined this block. Usually a pool of miners who had been involved in.

Size: size of the transaction obtained by adding the sizes of each transactions included in the block. This data is always provided in bytes.

The browser

In the same way as with an Internet browser, the user needs to enter a request to begin his search. It can be a transaction hash or TXID [6](sequence of 64 characters hexadecimal (0 to 9 and a to f) numbers used to uniquely identify a particular transaction) or a block height for example. Automatically, a page containing all the details about the transaction is loaded according to the request. Advanced information contains all the movements in this transaction and is only available at the user's request. Most of the time, a bitcoin transaction has several input and output addresses insofar as it allows a sender to save time and money by sending to several addresses at once. All the following data will be displayed:

TXID: as mentioned above

Input: transaction inputs are pointers to UTXO [7]. They point to a specific UTXO by reference to the transaction hash and sequence number where the UTXO is recorded in the blockchain.

Output: contains instructions for sending bitcoins [8].

Value: the number of Satoshi (1 BTC = 100,000,000 Satoshi) that this output will be worth when claimed.

ScriptPubKey: the second half of a script. There can be more than one output. Because each output from one transaction can only ever be referenced once by an input of a subsequent transaction, the entire combined input value needs to be sent in an output if the user doesn't want to lose it. [9] If the input is worth 50 BTC but a consumer only want to send 25 BTC, Bitcoin will create two outputs worth 25 BTC. This section is divided into two parts. The first, the top line, showing the total amount that the recipient has to receive in BTC, known as the destination. And the other part, below, showing the amount of bitcoins back to the user that remains in the wallet and which can be used as a new input in a subsequent transaction. Any input bitcoins not redeemed in an output is considered a transaction fee.

Transaction Fees: most transactions include transaction fees, which compensate the bitcoin miners for securing the network. Transaction fees serve as an incentive to include (mine) a transaction into the next block and also as a disincentive against “spam” transactions or any kind of abuse of the system, by imposing a small cost on every transaction. Transaction fees are collected by the miner who mines the block that records the transaction on the blockchain. [10]

Coinbase Data: This field must be between 2 and 100 bytes. Except for the first few bytes the rest of the coinbase data can be used by miners in any way they want; it is arbitrary data. In the genesis block, for example, Satoshi Nakamoto added the text “The Times 03/Jan/ 2009 Chancellor on brink of second bailout for banks” in the coinbase data, using it as a proof of the date and to convey a message. Currently, miners use the coinbase data to include extra nonce values and strings identifying the mining pool. [11]

List of blockchain explorers

Unless otherwise noted, all explorers support segwit addresses.


  1. Blockchain for dummies p 99 - Tiana Laurence - ISBN 978-1119365594
  2. Blockchain Enabled Application p.21 - David Metcalf - ISBN 978-1484230800
  3. Blockchain: A Practical Guide to Developing Business, Law, and Technology Solutions 1st Edition p.19- Joseph J. Bambara - ISBN 978-1260115871
  4. Mastering Bitcoin p.28 - Andreas M. Antonopoulos - ISBN 978-1491954386
  5. Blockchain: A Practical Guide to Developing Business, Law, and Technology Solutions 1st Edition p.18- Joseph J. Bambara - ISBN 978-1260115871
  6. beginning-blockchain-guide-building-solutions p.278 - Bikramaditya Singhal - ISBN 978-1484234433
  7. Blockchain Enabled Application p.18 - David Metcalf - ISBN 978-1484230800
  8. Blockchain Enabled Application p.18 - David Metcalf - ISBN 978-1484230800
  9. beginning-blockchain-guide-building-solutions p.201-202 - Bikramaditya Singhal - ISBN 978-1484234433
  10. Mastering Bitcoin p.127 - Andreas M. Antonopoulos - ISBN 978-1491954386
  11. Mastering Bitcoin p.225 - Andreas M. Antonopoulos - ISBN 978-1491954386