Block explorers

David Liu
Last edit: @liuzimin, September 25, 2020
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Block explorers are your portal to Ethereum's data. You can use them to see real-time data on blocks, transactions, miners, accounts, and other on-chain activity.

Prerequisites

You should understand the basic concepts of Ethereum so you can make sense of the data that a block explorer gives you. Start with an intro to Ethereum.

Services

Data

Ethereum is transparent by design so everything is verifiable. Block explorers provide an interface for getting this information. And this is for both the main Ethereum network and the testnets, should you need that data.

Here's a summary of the types of data you can get from a block explorer.

Blocks

New blocks are added to Ethereum every ~12 seconds (this can fluctuate) so there's a near-constant stream of data that gets added to block explorers. Blocks contain a lot of important data that you may find useful:

Standard data

  • Block height – The block number and length of the blockchain (in blocks) on creation of the current block
  • Timestamp – The time at which a miner mined the block
  • Transactions – The number of transactions included within the block
  • Miner – The address of the miner who mined the block
  • Reward – The amount of ETH awarded to the miner for adding the block (standard 2ETH reward + any transaction fees of transactions included in the block)
  • Difficulty – The difficulty associated with mining the block
  • Size – The size of the data within the block (measured in bytes)
  • Gas used – The total units of gas used by the transactions in the block
  • Gas limit – The total gas limits set by the transactions in the block
  • Extra data – Any extra data the miner has included in the block

Advanced data

  • Hash – The cryptographic hash that represents the block header (the unique identifier of the block)
  • Parent hash – The hash of the block that came before the current block
  • Sha3Uncles – ???
  • StateRoot – ????
  • Nonce – A value used to demonstrate proof-of-work for a block by the miner

Uncle blocks

Uncle blocks are created when two miners create blocks at near-enough the same time – only one block can be validated across the nodes. They are not included but still receive a reward for the work.

Block explorers provide information about uncle blocks like:

  • An uncle block number
  • A time they occurred
  • The block height at which they were created
  • Who mined it
  • The ETH reward

Gas

Not only will block explorers give you data about Gas usage in transactions and blocks, but some will give you information on the network's current gas prices. This will help you understand network usage, submit safe transactions and not overspend on gas. Look out for APIs that can help you get this information into your product's interface. Gas-specific data covers:

  • Estimated units of gas needed for a safe but slow transaction (+ estimated price and duration)
  • Estimated units of gas needed for an average transaction (+ estimated price and duration)
  • Estimated units of gas needed for a fast transaction (+ estimated price and duration)
  • Average confirmation time based on gas price
  • Contracts that are consuming gas – in other words, popular products that are seeing lots of usage on the network
  • Accounts that are spending gas – in other words, frequent network users

Transactions

Block explorers have become a common place for people to track the progress of their transactions. That's because the level of detail you can get provides extra certainty. Transaction data includes:

Standard data

  • Transaction hash – A hash generated when the transaction is submitted
  • Status – An indication of whether the transaction is pending, failed or a success
  • Block – The block in which the transaction has been included
  • Timestamp – The time at which a miner mined the transaction
  • From – The address of the account that submitted the transaction
  • To – The address of the recipient or smart contract that the transaction interacts with
  • Tokens transferred – A list of tokens that were transferred as part of the transaction
  • Value – The total ETH value being transferred
  • Transaction fee – The amount paid to the miner to process the transaction (calculated by gas price*gas used)

Advanced data

  • Gas limit – The maximum numbers of gas units this transaction can consume
  • Gas used – The actual amount of gas units the transaction consumed
  • Gas price – The price set per gas unit
  • Nonce – The transaction number for the from address (bear in mind this starts at 0 so a nonce of 100 would actually be the 101st transaction submitted by this account
  • Input data – Any extra information required by the transaction

Accounts

There's a lot of data that you can access about an account. This is why it's often recommended to use multiple accounts so that your assets and value can't be easily tracked. There are also some solutions being developed to make transactions and account activity more private. But here's the data that's available for accounts:

User accounts

  • Account address – The public address you can use to send funds to
  • ETH balance – The amount of ETH associated with that account
  • Total ETH value – The value of the ETH
  • Tokens – The tokens associated with the account and their value
  • Transaction history – A list of all the transactions where this account was either the sender or the recipient

Smart contracts

Smart contract accounts have all the data that a user account will have, but some block explorers will even display some code information too. Examples include:

  • Contract creator – The address that deployed the contract to mainnet
  • Creation transaction – The transaction that included the deployment to mainnet
  • Source code – The solidity or vyper code of the smart contract
  • Contract ABI – The Application Binary Interface of the contract – the calls the contract makes and the data received
  • Contract creation code – The compiled bytecode of the smart contract – created when you compile a smart contract written in Solidity or Vyper, etc.
  • Contract events – A history of the methods called in the smart contract. Basically a way to see how the contract is being used and how often

Tokens

Token are a type of contract so they'll have similar data to a smart contract. But because they have value and can be traded they have additional data points:

  • Type – Whether they're an ERC-20, ERC-721 or another token standard
  • Price – If they're an ERC-20 they'll have a current market value
  • Marketcap – If they're an ERC-20 they'll have a market cap (calculated by price*total supply)
  • Total supply – The number of tokens in circulation
  • Holders – The number of addresses that hold the token
  • Transfers – The number of times the token has been transferred between accounts
  • Transaction history – A history of all the transactions including the token
  • Contract address – The address of the token that was deployed to mainnet
  • Decimals – ERC-20 tokens are divisible and have decimal places

Network

Of course there's some data that speaks to the health of the network. These are quite specific to Ethereum's proof-of-work consensus mechanism. When Ethereum transitions to Eth2 some of this data will be redundant

  • Difficulty – The current mining difficulty
  • Hash rate – An estimate of how many hashes are being generated by Ethereum miners trying to solve the current Ethereum block or any given block.
  • Total transactions – The number of transactions since Ethereum was created
  • Transactions per second – The number of transactions processable withing a second
  • ETH price – The current valuations of 1 ETH
  • Total ETH supply – Number of ETH in circulation – remember new ETH is created with the creation of every block in the form of block rewards
  • Marketcap – Calculation of price*supply

Eth2 data

Eth2 is still in development but it's worth talking about some of the data points that explorers will be able to provide you. In fact, all of this data is available right now for the testnets.

If you're not familiar with Eth2 check out our Eth2 overview.

Epoch

In Eth2, the beacon chain creates committees of validators which are randomised at the end of every epoch (every 6.4 minutes) for security reasons. Epoch data includes:

  • Epoch number
  • Finalized status – Whether the epoch has been finalised (Yes/No)
  • Time – The time the epoch ended
  • Attestations – The number of attestations in the epoch (votes for blocks within slots)
  • Deposits – The number of ETH deposits included in the epoch (validators must stake ETH to become validators)
  • Slashings – Number of penalties given to proposers of blocks or attestors
  • Voting participation – The amount of staked ETH used to attest blocks
  • Validators – Number of validators active for the epoch
  • Average Validator balance – Average balance for active validators
  • Slots – Number of slots included in the epoch (slots include one valid block)

Slot

Slots are opportunities for block creation, the data available for each slot includes:

  • Epoch – The epoch in which the slot is valid
  • Slot number
  • Status – The status of the slot (Proposed/Missed)
  • Time – The slot timestamp
  • Proposer – The validator that proposed the block for the slot
  • Block root – ?
  • Parent root – The hash of the block that came before
  • State root – ?
  • Signature – ?
  • Randao reveal – ?
  • Graffiti
  • ETH1data
    • Block hash
    • Deposit count
    • Deposit root
  • Attestations – Number of attestations for the block in this slot
  • Deposits – The number of deposits during this slot
  • Voluntary exits – The number of validators that left during the slot
  • Slashings – Number of penalties given to proposers of blocks or attestors
  • Votes – The validators that voted for the block in this slot
  • Attestations – The number of attestations for the block in this slot

Blocks

In Eth2 blocks work differently because miners are replaced by validators and the beacon chain introduces slots and epochs to Ethereum. So that means new data!

  • Proposer – The validator that was algorithmically chosen to propose the new block
  • Epoch – The epoch in which the block was proposed
  • Slot – The slot in which the block was proposed
  • Attestations – The number of attestation included in the slot. Attestations are like votes that indicate the block is ready to go to the beacon chain

Validators

Validators are responsible for proposing blocks and attesting to them within slots.

  • Validator number – Unique number that represents the validator
  • Current balance – The validator's balance including rewards
  • Effective balance – The validator's balance that is used for staking
  • Income – The rewards or penalties receivedd by the validator
  • Status – Whether the validator is currently online and active or not
  • Attestation effectiveness – The average time it takes for the validator's attestations to be included in the chain
  • Eligibility for activation – Date (and epoch) when the validator became available to validate
  • Active since – Date (and epoch) when the validator became active
  • Proposed blocks – The block that the validator has proposed
  • Attestations – The attestations that the validator has provided
  • Deposits – The from address, transaction hash, block number, timestamp, amount and status of the staking deposit made by the validator

Attestations

Attestations are "yes" votes to include blocks in the chain. Their data relates to a record of the attestation and the validators who attested

  • Slot – The slot in which the attestation took place
  • Committee index – ?
  • Aggregation bits – ?
  • Validators – The validators that provided attestations
  • Beacon block root – ?
  • Source – ?
  • Target – ?
  • Signature – ?

Network

The Eth2 top-level data includes the following:

  • Current epoch
  • Current slot
  • Active validators – Number of active validators
  • Pending validators – Number of validators waiting for to be made active
  • Staked ETH – Amount of ETH staked in the network
  • Average balance – Average ETH balance of validators

Block explorers

  • Etherscan – a block explorer you can use to fetch data for Ethereum Mainnet, Ropsten Testnet, Kovan Testnet, Rinkeby Testnet, and Goerli Testnet.
  • Blockscout – focusses on the following networks:
    • xDai – a clever combination of MakerDAO's DAI stablecoin and POA's sidechain and tokenbridge technology
    • POA – A sidechain and autonomous network secured by a group of trusted validators. All validators on the network are United States notaries, and their information is publicly available.
    • POA Sokol Testnet
    • ARTIS – an Ethereum compliant blockchain
    • LUKSOL14 – ?
    • qDai – ?
  • Etherchain – a block explorer for the Ethereum mainnet.
  • Ethplorer – a block explorer with a focus on tokens for the Ethereum mainnet and the Kovan testnet.

Eth2 block explorers

Further reading

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