eth_getFilterChanges

eth_getFilterChanges polls an existing filter on Polygon PoS (chain ID 137) and returns only what is new since your previous call — log objects for a log filter, block hashes for a block filter, or transaction hashes for a pending-transaction filter. On Polygon, where MATIC-paid blocks arrive about every two seconds, this is the standard HTTP way to keep up with QuickSwap swaps or stablecoin transfers without re-sending the filter criteria each time. Aim your polling loop at https://polygon.therpc.io/YOUR_API_KEY and each call hands back just the events recorded since the last poll.

Use cases

• Poll on a short interval (Polygon blocks land roughly every 2 seconds) to stream new log events for a contract without re-specifying address and topics on every request.
• Drive a block-tick loop: register a block filter once with eth_newBlockFilter, then call eth_getFilterChanges repeatedly to receive each new Bor block hash as it is produced.

Parameters

Response

Example request

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getFilterChanges",
7    "params": ["0x1"],
8    "id": 1
9  }'

Try it live in the Polygon playground.

Errors & troubleshooting

Common pitfalls

• Filters are dropped after about five minutes of inactivity; catch the filter not found error and recreate the filter, then resume polling.
• For log filters, always check each entry's removed field — Polygon can reorg recent Bor blocks before they are checkpointed to Ethereum, and reorged logs come back marked removed: true.
• Tune the interval: polling many times a second burns CUs needlessly, while polling slower than the ~5-minute expiry window risks losing the filter between calls.

Supported networks

• Mainnet — Chain ID: 137
• Amoy — Chain ID: 80002

See also

• eth_newFilter
• eth_newBlockFilter
• eth_newPendingTransactionFilter
• eth_uninstallFilter

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_getFilterChanges","params":["0x1"]}'