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

# eth_createAccessList

> Creates an EIP-2930 access list that specifies which addresses and storage keys a transaction will access, helping optimize gas usage and reduce out-of-gas errors.

### Parameters

<ParamField query="chainId" type="string" default="100" required>
  Unique identifier for a blockchain network.
</ParamField>

<ParamField body="id" type="number" default={1} required>
  Request identifier used to match responses.
</ParamField>

<ParamField body="jsonrpc" type="string" default="2.0" required>
  JSON-RPC version.
</ParamField>

<ParamField body="method" type="string" default="eth_createAccessList" required>
  JSON-RPC method name.
</ParamField>

<ParamField body="params" type="object" default={[{"from":"0xaeA8F8f781326bfE6A7683C2BD48Dd6AA4d3Ba63","to":"0xa02457e5dfd32bda5fc7e1f1b008aa5979568150","data":"0x608060806080608155"},"pending"]} placeholder="[{&#x22;from&#x22;:&#x22;0xaeA8F8f781326bfE6A7683C2BD48Dd6AA4d3Ba63&#x22;,&#x22;to&#x22;:&#x22;0xa02457e5dfd32bda5fc7e1f1b008aa5979568150&#x22;,&#x22;data&#x22;:&#x22;0x608060806080608155&#x22;},&#x22;pending&#x22;]" required>
  Parameters: \[transaction call object, block identifier]

  Positional parameters for <code>eth\_createAccessList</code>:

  <ul>
    <li><code>params\[0]</code>: Transaction call object used to simulate the access list.</li>
    <li><code>params\[1]</code>: Block identifier: number, block hash, or tag ("latest", "earliest", "pending", "safe", or "finalized").</li>
  </ul>
</ParamField>

### Returns

<ResponseField name="result" type="object">
  Access list and estimated gas usage.

  <Expandable title="properties">
    <ResponseField name="accessList" type="array">
      List of addresses and storage keys accessed.

      <Expandable title="items">
        <ResponseField name="items[]" type="object">
          <Expandable title="properties">
            <ResponseField name="address" type="string">
              Hex-encoded address accessed.
            </ResponseField>

            <ResponseField name="storageKeys" type="array">
              List of accessed storage keys.

              <Expandable title="items">
                <ResponseField name="items[]" type="string" />
              </Expandable>
            </ResponseField>
          </Expandable>
        </ResponseField>
      </Expandable>
    </ResponseField>

    <ResponseField name="gasUsed" type="string">
      Estimated gas usage with the generated access list (hex).
    </ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash Curl theme={null}
  curl --request POST \
    --url https://api.uniblock.dev/uni/v1/json-rpc?chainId=100 \
    --header 'content-type: application/json' \
    --data '{
      "id": 1,
      "jsonrpc": "2.0",
      "method": "eth_createAccessList",
      "params": [
        {
          "from": "0xaeA8F8f781326bfE6A7683C2BD48Dd6AA4d3Ba63",
          "to": "0xa02457e5dfd32bda5fc7e1f1b008aa5979568150",
          "data": "0x608060806080608155"
        },
        "pending"
      ]
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json Success theme={null}
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": {
      "accessList": [
        {
          "address": "0xa02457e5dfd32bda5fc7e1f1b008aa5979568150",
          "storageKeys": [
            "..."
          ]
        }
      ],
      "gasUsed": "0x125f8"
    }
  }
  ```
</ResponseExample>