eth_newFilter

eth_newFilter creates a server-side log filter on OP Mainnet — the ETH-gas OP Stack rollup at chain ID 10 (0xa) — and returns a hex filter ID. You define the criteria once (a block range, one or more contract addresses, and indexed topics), then poll the ID with eth_getFilterChanges to pull only the matching logs emitted since your last poll, without re-sending the full filter each time. This is the polling counterpart to a WebSocket eth_subscribe logs subscription. Create the filter against https://optimism.therpc.io/YOUR_API_KEY.

Use cases

• Poll for new ERC-20 Transfer events on an OP Mainnet token by setting address and the Transfer topic once, then calling eth_getFilterChanges on a short interval — every couple of blocks, since OP Mainnet produces one roughly every 2 seconds.
• Monitor a DEX pair for Swap events in a long-running process — for example a Velodrome pool — by registering its address and topic and incrementally draining new logs as trades land.

Parameters

Response

Example request

1curl https://optimism.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_newFilter",
7    "params": [{}],
8    "id": 1
9  }'

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• An idle filter expires after a few minutes (commonly ~5) without polling; implement recreation logic so that when eth_getFilterChanges returns filter not found, you re-register the filter and continue from the last block you processed.
• Filter state lives on the node and is connection-scoped, so it is lost on reconnect or when load-balanced to a different node; always be ready to recreate the filter rather than assuming the ID persists.
• For real-time event streaming, a WebSocket eth_subscribe logs subscription is more efficient than repeatedly polling a filter — reserve eth_newFilter for HTTP-only or batch-style consumers.

Supported networks

• Mainnet — Chain ID: 10
• Sepolia — Chain ID: 11155420

See also

• eth_getFilterChanges
• eth_getFilterLogs
• eth_uninstallFilter
• eth_getLogs

1curl https://optimism.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_newFilter","params":[]}'