Reading this question and this one, it's not clear to me whether the full nodes execute contract code for free. From my understanding, the client has to pay an amount of ether prior to making a transaction to a contract (startgas) and then an amount (gasprice) for each transaction.

The client pays this amount in order to execute the contract but when miners (full nodes) execute the contract for confirmation, do they do so for free?

1 Answer 1


Miners != Full nodes. Today there are no light client available on Ethereum. But to mine, you don't need a Full node (on BTC, it is the case. on Ethereum we will see). Full Node check the blocks for free, to be sure to have a valid blockchain. You have no reward.

But Miners should have a Full Node to check they're working on real and valid datas. If you are mining on corrupted/wrong datas, you have no chance of gain. And the miner can't accept bad blocks; if a miner who send bad blocks to stop other miners to mine, it will be terrible. So, all miners have to check incoming blocks for the consensus resolution.

  • But isn't mining validating a block (and its contents)? So do they validate only a portion of a block chain? What is the difference between the checking done by full nodes and mining? So, full node == node with a copy of the whole blockchain? Why would a full node check(mine?) for free when it could do the same in exchange for Ether? So a miner can't accept bad blocks (with invalid headers). That is logical, but a full node can?
    – Sebi
    Jun 25, 2016 at 17:54

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