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Introducing the Nonce

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What is the Nonce and its "optional" use (with Tatum)

In blockchain technology, the nonce is a transaction counter that helps to prevent double-spending and replay attacks on a blockchain network. This value is attached to each Ethereum and EVM-compatible (Account Model) chain sender address.

Ethereum and other EVM-compatible blockchains require the nonce value for each transaction to ensure that the same transaction is not executed twice and that no one can replay a previously sent transaction.

With Tatum, when the nonce is not specified when making a transaction on Ethereum and other EVM-compatible chains, our Engine automatically adds it based on the sender's address.

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The Tatum engine has a delay when automatically calculating the nonce. Users with a high transaction broadcast volume should use a manual nonce value. Otherwise, errors about "replacement transaction" will be common.

Finding the nonce value

v3 REST API

You can get the current nonce value for an EVM-compatible blockchain address by making an API call:

Example request:

curl --location 'https://api.tatum.io/v3/ethereum/transaction/count/0x271ebc3C939Db4d0######' \
--header 'x-api-key: {Mainnet_API_KEY}'
//response:
4887 // Current nonce value in decimals

RPC node request

You can also get the current nonce value using an Ethereum node's RPC call.

Example:

curl --location 'https://api.tatum.io/v3/blockchain/node/ETH/' \
--header 'x-api-key: {Mainnet_API_KEY}' \
--header 'Content-Type: application/json' \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getTransactionCount",
    "params":[
        "0x271ebc3C939Db4d0######'",
        "latest"
        ],
    "id":1
    }'
//response:
{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x1316" //needs conversion to decimal
}

Nonce value and dropped transactions

Single transaction

If a transaction with nonce value X is dropped or doesn't get included in a block, the nonce value for that account doesn't increase. The nonce is only increased once a transaction is successfully included in a block.

Multiple transactions

If you try to send multiple transactions at the same time, each transaction must have nonce+1, nonce+2, nonce+3, nonce+4, etc. If for some reason the transaction with nonce+2 gets dropped (low gas price, network congestion, etc.), the transactions with values nonce+3 and nonce+4 will be stuck in the mempool and won't be mined until the transaction with nonce+2 is mined.

To solve this, you would need to re-send the transaction with nonce+2 with enough gas for it to be mined. Once the transaction with nonce+2 would be mined, any subsequent transactions with higher nonce value should be able to be mined too.

Updated 5 days ago