> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# eth_getUncleCountByBlockHash | Optimism

> Optimism API method that retrieves the number of uncles in a block, identified by its hash. eth_getUncleCountByBlockHash on Optimism via Chainstack.

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

## Parameters

* `hash` — the hash of the block for which the uncle count is being queried, as a hexadecimal string.

## Response

* `result` — the number of uncles in the specified block, encoded as a hexadecimal string. This count includes all uncles that were referenced by the block when it was mined.

## Use case

The `eth_getUncleCountByBlockHash` method is useful for applications that analyze blockchain security and decentralization aspects, such as block explorers or network analysis tools. It can help these applications understand the level of block competition and the rate at which uncles are included in the blockchain.


## OpenAPI

````yaml openapi/optimism_node_api/eth_getUncleCountByBlockHash.json POST /efb0a5eccd2caa5135eb54eba6f7f300
openapi: 3.0.0
info:
  title: eth_getUncleCountByBlockHash example
  version: 1.0.0
  description: This is an API example for eth_getUncleCountByBlockHash.
servers:
  - url: https://optimism-mainnet.core.chainstack.com
security: []
paths:
  /efb0a5eccd2caa5135eb54eba6f7f300:
    post:
      tags:
        - Ethereum Operations
      summary: eth_getUncleCountByBlockHash
      operationId: getUncleCountByBlockHash
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                jsonrpc:
                  type: string
                  default: '2.0'
                method:
                  type: string
                  default: eth_getUncleCountByBlockHash
                id:
                  type: integer
                  default: 1
                params:
                  type: array
                  items:
                    anyOf:
                      - type: string
                        default: >-
                          0x7e4aea365093a183b0df5f003f26144ef04ec8a6e7f4910356590c5fc7b1671f
                  default:
                    - >-
                      0x7e4aea365093a183b0df5f003f26144ef04ec8a6e7f4910356590c5fc7b1671f
      responses:
        '200':
          description: The uncle count of the block by hash
          content:
            application/json:
              schema:
                type: object
                properties:
                  jsonrpc:
                    type: string
                  id:
                    type: integer
                  result:
                    type: string

````