eth_newFilter

eth_newFilter creates a server-side log filter on Base — Coinbase's ETH-gas OP Stack rollup — from a filter object describing the fromBlock/toBlock range, one or more contract address values, and topics to match. It returns a hex filter ID you then poll incrementally with eth_getFilterChanges, so each poll returns only the logs that have appeared since your previous call instead of re-scanning the whole range. Register the filter against https://base.therpc.io/YOUR_API_KEY (Base mainnet, chain ID 8453 / 0x2105). It pairs naturally with the busy Base log stream from apps like Aerodrome and Uniswap.

Use cases

• Poll for new ERC-20 Transfer events on a Base token on a fixed interval (a few seconds suits Base's ~2s blocks) without re-specifying the full filter object on every request.
• Monitor a DEX pair or pool contract — for instance an Aerodrome or Uniswap pool on Base — for Swap events from a long-running indexer or bot process.

Parameters

Response

Example request

1curl https://base.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 Base playground.

Errors & troubleshooting

Common pitfalls

• Filters are dropped after roughly 5 minutes of inactivity; implement recreation logic so that when eth_getFilterChanges returns a filter-not-found error you call eth_newFilter again and continue.
• Server-side filter state is connection-scoped and is lost on reconnect or node failover, so always be ready to recreate the filter rather than assuming the ID survives.
• For real-time event delivery, a WebSocket eth_subscribe("logs", ...) is more efficient than repeatedly polling a filter on Base; reserve eth_newFilter for HTTP-only or batch-style consumers.

Supported networks

• Mainnet — Chain ID: 8453
• Sepolia — Chain ID: 84532

See also

• eth_getFilterChanges
• eth_getFilterLogs
• eth_uninstallFilter
• eth_getLogs

1curl https://base.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":[]}'