eth_newFilter

eth_newFilter creates a server-side log filter on the Avalanche C-Chain (chain ID 43114, gas paid in AVAX) and returns a hex filter ID. You define which logs you care about — by block range, contract address, and indexed topics — once, then poll the ID with eth_getFilterChanges to receive only the new matching logs since your last poll, without re-sending the full filter each time. This is the efficient way to watch contract events such as ERC-20 transfers or DEX swaps over a long-running connection. Create the filter at https://avalanche.therpc.io/YOUR_API_KEY.

Use cases

• Poll for new ERC-20 Transfer events on a short interval — the C-Chain's ~1–2s block time means a few-second poll keeps up — without re-specifying the full filter on every call.
• Monitor a DEX pair contract (for example a Trader Joe liquidity pool) for Swap events from a long-running indexer or bot.

Parameters

Response

Example request

1curl https://avalanche.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 Avalanche playground.

Errors & troubleshooting

Common pitfalls

• Filters are dropped after a few minutes (around 5) of inactivity; when eth_getFilterChanges returns filter not found, recreate the filter and continue from where you left off.
• Server-side filter state is tied to the connection and is lost on reconnect or when load-balanced to a different node — always be ready to recreate the filter rather than assuming it persists.
• For real-time event delivery, eth_subscribe over a WebSocket connection is more efficient than repeatedly polling a filter; reserve polling for HTTP-only setups.

Supported networks

• Mainnet — Chain ID: 43114
• Fuji

See also

• eth_getFilterChanges
• eth_getFilterLogs
• eth_uninstallFilter
• eth_getLogs

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