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POST
/
efb0a5eccd2caa5135eb54eba6f7f300
eth_getUncleCountByBlockNumber
curl --request POST \
  --url https://optimism-mainnet.core.chainstack.com/efb0a5eccd2caa5135eb54eba6f7f300 \
  --header 'Content-Type: application/json' \
  --data '
{
  "jsonrpc": "2.0",
  "method": "eth_getUncleCountByBlockNumber",
  "id": 1,
  "params": [
    "0x6ecf0b4"
  ]
}
'
{
  "jsonrpc": "<string>",
  "id": 123,
  "result": "<string>"
}

Documentation Index

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Optimism API method that retrieves the number of uncles in a block, identified by its number. Uncles are blocks that are not part of the main blockchain but are still valid and have a relationship to a block on the main chain.
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​
Parameters

  • blockNumber — the number of the block for which the uncle count is being queried, encoded as a hexadecimal string.

​
Response

  • result — the number of uncles in the specified block, encoded as a hexadecimal string. This includes all uncles that were referenced by the block at the time it was sealed.

​
Use case

The eth_getUncleCountByBlockNumber method is important for applications that monitor the health and security of the blockchain, such as network analysis tools or block explorers. It provides insights into the level of competition among miners and the overall inclusiveness of the blockchain towards valid blocks that did not make it to the main chain.

Body

application/json
​
jsonrpc
string
default:2.0
​
method
string
default:eth_getUncleCountByBlockNumber
​
id
integer
default:1
​
params
string[]

Response

200 - application/json

The uncle count of the block by number

​
jsonrpc
string
​
id
integer
​
result
string
Last modified on May 1, 2026