mainnet.base.org / sepolia.base.org) are Flashblocks-enabled, exposing all standard Ethereum JSON-RPC methods plus a set of pre-confirmation-specific additions. These let you read state, simulate transactions, and stream events against sequencer-ordered data up to ~1.8 seconds before a block seals.
All standard Ethereum JSON-RPC methods support the
"pending" block tag to resolve against pre-confirmed state instead of the transaction pool. See the RPC Overview for endpoint URLs.HTTP Methods
| Method | Description |
|---|---|
| eth_simulateV1 | Simulate transaction bundles against pre-confirmed state |
| base_transactionStatus | Check if a transaction has been received by the node mempool |
WebSocket Subscriptions
On a Flashblocks WSS endpoint,eth_subscribe with newHeads emits a new event approximately every 200ms per Flashblock instead of every 2 seconds. Three additional subscription types are also available that are exclusive to Flashblocks endpoints:
| Subscription | Description |
|---|---|
| newFlashblockTransactions | Stream individual transactions as they are pre-confirmed (~200ms each) |
| pendingLogs | Stream filtered event logs from pre-confirmed transactions |
| newFlashblocks | Stream full Flashblock payload objects from the sequencer |