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POST
/
efb0a5eccd2caa5135eb54eba6f7f300
eth_newPendingTransactionFilter
curl --request POST \
  --url https://optimism-mainnet.core.chainstack.com/efb0a5eccd2caa5135eb54eba6f7f300 \
  --header 'Content-Type: application/json' \
  --data '
{
  "jsonrpc": "2.0",
  "method": "eth_newPendingTransactionFilter",
  "id": 1
}
'
{
  "jsonrpc": "<string>",
  "id": 123,
  "result": "<string>"
}
Optimism API method that creates a filter in the node to notify when new pending transactions are received. To check if the state has changed, call eth_getFilterChanges with the filter ID returned by this method.
On Optimism, this method returns an empty array — the mempool is private to the sequencer, so there are no public pending transactions to surface. For real-time pre-confirmed transactions, poll the pending block tag (Flashblocks) instead — see Track real-time transactions on Optimism with Flashblocks.
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​
Parameters

  • none

​
Response

  • result — a string representing the filter ID. This ID should be used in subsequent calls to eth_getFilterChanges to retrieve new pending transactions.

​
Use case

The eth_newPendingTransactionFilter method is useful for applications that need to monitor the mempool for new transactions. Common use cases include:
  • Building transaction monitoring tools
  • Creating real-time transaction tracking interfaces
  • Implementing MEV (Maximal Extractable Value) strategies
  • Monitoring specific addresses for pending transactions
On Optimism, these patterns are not served by eth_newPendingTransactionFilter — the mempool is private to the sequencer, so the filter returns no pending transactions, and the eth_subscribe("newPendingTransactions") subscription stays empty too. Optimism exposes Flashblocks through the pending block tag rather than WebSocket subscriptions, so poll eth_getBlockByNumber with the pending tag to track pre-confirmed transactions — see Track real-time transactions on Optimism with Flashblocks. Note: After creating the filter, you need to poll eth_getFilterChanges periodically to get updates. Filters timeout if they’re not used for a period of time, so applications should be prepared to recreate them if necessary.

Body

application/json
​
jsonrpc
string
default:2.0
​
method
string
default:eth_newPendingTransactionFilter
​
id
integer
default:1

Response

200 - application/json

The ID of the created pending transaction filter

​
jsonrpc
string
​
id
integer
​
result
string
Last modified on June 26, 2026