How the Electroneum Smart Chain seals a block

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Just sealed

pending transaction this round's proposer and its PRE-PREPARE PREPARE: a validator has checked the block COMMIT: a validator's seal; six make the block final ROUND-CHANGE: the proposer went quiet validator that proposed the latest block transaction in that block, succeeded included but reverted, gas still paid committed seal counted from the block header

Wallets send signed transactions to any node on the network, and nodes relay them to their peers. Within a second the nine validators hold much the same pool of candidates. Addresses, gas and the virtual machine are Ethereum's; the coin is ETN.
Consensus runs in numbered rounds at each block height. The job of proposing rotates through the validator list one seat per block, so every validator proposes once every 45 seconds. The proposer of round 0 packs transactions into a block and broadcasts it as a PRE-PREPARE message.
Each validator checks the block: the proposer is the right one for this round, the transactions execute, the state root matches. If so it broadcasts a PREPARE for that block hash to every other validator. Once a validator has seen 6 of 9 PREPAREs, two thirds of the set, the block is prepared: it will not vote for a different block at this height.
A prepared validator signs the block hash and broadcasts that signature as a COMMIT. Six seals are a quorum. The proposer writes them into the block header, and every node that sees a block carrying six valid seals accepts it at once. There is no probability here, no waiting for more blocks on top: the seals are the finality.
The sealed block joins the chain and the next height begins with the next validator in the list as proposer. Fees follow Ethereum's model: the base fee is burned and the tip goes to the validator that proposed the block. Five seconds after this block, the next one lands.
If no valid PRE-PREPARE arrives before the round timer runs out, validators broadcast a ROUND-CHANGE. When six agree, the round number goes up and the next validator in the list proposes instead. Nothing was sealed, so nothing has to be undone. This is what lets two of the nine validators fail without stopping the chain.

PRE-PREPARE, PREPARE and COMMIT travel privately between validators. Public nodes publish each sealed block, and its header carries the round number and the committed seals, which is what live mode draws. Pick any step to study it in step-by-step mode.

Transaction types, by share of each block Waiting for the first full block

How this is counted

Every transaction in a block counts once, by what it does: a plain ETN transfer (no input data), a token transfer or approval (recognised by the ERC-20 function selector in the input), any other contract call, or a contract creation (no recipient). Reverted transactions still count toward their type. ETN transfers always get the first colour.

Transactions per block Waiting for the first block

succeeded
reverted (included, gas still paid)
before you connected

Block chain 0 tx in latest block 0.000000 ETN paid in gas 9 validators 0 of 9 seals on latest block

The parts that make this work

From CryptoNote to a smart chain

Electroneum launched in 2017 as a Monero-derived, CryptoNote proof-of-work coin aimed at phone users. In July 2019 it abandoned open mining for a "moderated blockchain": a permissioned system its team called Proof of Responsibility, in which approved NGOs ran the validators and kept the block rewards for their work. In early 2024 the project replaced that chain altogether. The Electroneum Smart Chain, released as version 6.0.0 "Aurelius" on 29 February 2024, is a fork of go-ethereum with chain id 52014 and full EVM compatibility. The legacy chain was forked on 5 March 2024 at block 1,811,310 to open a one-way bridge, and holders moved their ETN across one for one. This page models the smart chain; the old chain is no longer produced.

Rounds, PREPARE and COMMIT

The consensus engine is Istanbul BFT. Electroneum's documentation calls it IBFT; the code in its node is the QBFT-lineage engine from GoQuorum, the family that succeeded IBFT 2.0, and the message flow is the same in all of them. Each block height runs in rounds. The proposer of a round broadcasts the block as a PRE-PREPARE. Every validator that finds it valid broadcasts a PREPARE. A validator that has collected PREPAREs from two thirds of the set is prepared and broadcasts a COMMIT, which is its signature over the block hash. Two thirds of the COMMITs form a quorum. With nine validators that is six, and the protocol tolerates two of them being offline or dishonest: three faulty out of nine would be enough to block a quorum or, in the worst case, to split it. The header of every block lists the validator addresses, the round in which it was sealed, and the committed seals themselves, so the count you see in live mode is read straight from the chain.

Final at once, not eventually

On Bitcoin a block is never final. Each block on top makes a reorganisation less likely, so exchanges wait for six or more, about an hour. Ethereum's proof of stake finalises a block after two epochs, around thirteen minutes. On the Electroneum Smart Chain a block that carries six valid seals cannot be replaced: a competing block at the same height would need six seals of its own, and the honest validators that signed the first one will not sign a second. So the block is final the moment it is published, five seconds after the previous one. Explorers and wallets need no confirmation count.

Nine validators, and who runs them

This is a permissioned network. Every block header on mainnet lists the same nine validator addresses, and they propose in a fixed order, one after another. Electroneum says the validators are run by vetted NGOs, universities and partner organisations it has selected, continuing the model of its 2019 chain, but the addresses are not labelled on the public explorer, so this page cannot say which organisation runs which node. Validators can be added or removed by a majority vote of the existing validators, recorded in block headers and tallied over a 17,280-block voting epoch. A whitepaper published in June 2025 proposes replacing this with a permissionless system, where anyone who locks enough ETN can stand as a candidate, with an initial target of 24 active validators and daily epochs. As of September 2026 that system is not live: the header still carries nine fixed validators.

What a transaction costs

The smart chain uses Ethereum's gas accounting and its EIP-1559 fee model. A plain ETN transfer takes 21,000 gas, and blocks target 15 million gas with a hard limit of 30 million. Mainnet blocks usually carry under a million gas, so the base fee has sunk to its floor of 7 wei, which is nothing at all. Wallets add a tip of about 1 gwei per gas, so a transfer costs roughly 0.000021 ETN. The base fee is burned; the tip goes to the validator that proposed the block. There is no block reward beyond that.

Round changes

The block proposer is decided in advance, so a validator that is down or unreachable leaves a gap. Validators wait for a fixed timeout, then broadcast a ROUND-CHANGE message for the next round. Six of those move everyone to the new round, whose proposer is the next validator in the list. If a block had already been prepared by some validators, the new proposer must re-propose that same block, which is what keeps two rounds from sealing different blocks at one height. Every mainnet block this page has seen was sealed in round 0, so round changes are rare; the header's round field will show one if it happens while you watch.

What live mode shows

Live mode polls a public Electroneum mainnet JSON-RPC node every two seconds and draws each new block as it lands. The ring is the real validator list decoded from the block header, the validator that lights up is the block's real proposer, and the arc fills to the real number of committed seals in that header. The node does not say which validators produced the seals, so the seal beams are spread around the ring. Each dot is a real transaction, red if it reverted. Block numbers, hashes, rounds, transaction counts and the ETN paid in gas are real, the last computed from each transaction's receipt. PREPARE messages never reach public nodes, so live mode shows the proposal and the seals only.

What the animation simplifies

Step-by-step mode shows a round change in every cycle so you can see one; on mainnet they are rare. Messages are drawn one by one, though real validators send them at once, and the whole protocol finishes well within the five-second block interval. Transaction counts in step-by-step mode are illustrative, and the model ignores the validator voting that can change the set. The protocol and the header format are described in the Electroneum developer documentation.