Flashblocks: Query
https://mainnet.base.org with "pending" to fetch the live Flashblock in progress — a real block object updated every ~200ms with new pre-confirmed transactions. The response shape is identical; the block is simply not yet sealed.Parameters
string
required
Block number in hex, or
"latest", "pending", "safe", "finalized", "earliest". Use "pending" to get the in-progress block.boolean
required
If
true, returns full transaction objects. If false, returns only transaction hashes.Returns
object
A block object, or
null if no block was found.Show Block fields
Show Block fields
string
Block number in hex.
null when pending.string
Block hash.
null when pending.string
Hash of the parent block.
string
PoW nonce. Always
"0x0000000000000000" on Base (PoS).string
Hash of the uncles list. Always empty on Base.
string
Bloom filter for the block’s logs.
string
Root of the transaction trie.
string
Root of the final state trie.
string
Root of the receipts trie.
string
Address of the fee recipient (coinbase).
string
Always
"0x0" on Base (PoS).string
Present in all blocks; repurposed for PoS consensus (bytes32 hex).
string
Arbitrary data field set by the sequencer.
string
Block size in bytes (hex).
string
Maximum gas allowed in this block (hex).
string
Total gas used in this block (hex).
string
Unix timestamp (hex).
array
Array of transaction hashes or full transaction objects.
array
Always
[] on Base.array
Always
[] on Base.string
Merkle root of the withdrawals list (EIP-4895, bytes32 hex).
string
EIP-1559 base fee per gas (hex).
string
Total blob gas used (EIP-4844, hex).
string
Excess blob gas for blob fee calculation (EIP-4844, hex).
string
Parent beacon block root (EIP-4788).
string
Hash of requests (EIP-7685).
Flashblock-Specific Response Fields
When querying"pending", the response is a live snapshot of the block being built. A few fields behave differently:
| Field | Standard latest | Flashblocks pending |
|---|---|---|
number | Sealed block number | Current block number (being built) |
hash | Final block hash | Hash of the partial block at this Flashblock index |
gasUsed | Final gas used | Cumulative gas used up to this Flashblock |
transactions | All sealed transactions | Transactions pre-confirmed so far |
blobGasUsed | Final blob gas used | Propagated from cumulative Flashblock state |
Example
curl https://mainnet.base.org \
-X POST \
-H "Content-Type: application/json" \
-d '{
"jsonrpc": "2.0",
"method": "eth_getBlockByNumber",
"params": ["latest", false],
"id": 1
}'
curl https://mainnet.base.org \
-X POST \
-H "Content-Type: application/json" \
-d '{
"jsonrpc": "2.0",
"method": "eth_getBlockByNumber",
"params": ["pending", false],
"id": 1
}'
{
"jsonrpc": "2.0",
"id": 1,
"result": {
"baseFeePerGas": "0x4c4b40",
"blobGasUsed": "0x5384cc",
"difficulty": "0x0",
"excessBlobGas": "0x0",
"extraData": "0x01000000640000000500000000004c4b40",
"gasLimit": "0x17d78400",
"gasUsed": "0x2155bc7",
"hash": "0x491bca01d4bc076d60833dbd973fe031a74e7ae31866bf70d077619e09edb6ff",
"logsBloom": "0xb765d5b0...",
"miner": "0x4200000000000000000000000000000000000011",
"mixHash": "0x47aecef0e1afa26b8e1f428e9a8696cf53d85c62587d8c2cea079c715cd29626",
"nonce": "0x0000000000000000",
"number": "0x2c31b0b",
"parentBeaconBlockRoot": "0x15b9e7c8ac4cbe92dafc849ed30a23e91624bbe5cbe199c0ccea3f7de7fc6d49",
"parentHash": "0x89f4c9e23a2f706f0afa9ca8f770c4b7dcbcb73ba7e9b1c29c4a8c1b90c31d24",
"receiptsRoot": "0x5a428d77344334537d7adaf85a45eb6d7977bc807a68c669f36cb043600da6d2",
"requestsHash": "0xe3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
"sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
"size": "0x1bb3b",
"stateRoot": "0x1b1525af0cdd504147b89f2a7ce1838ccb70c5439c45ce55522c2e2529801e87",
"timestamp": "0x6a1092f9",
"transactions": [
"0x03c8f106f18ad94190e763e21b584c5825b2f4c61f1274c0e8abe65b4476cd51",
"..."
],
"transactionsRoot": "0x6b9c9fcbdf98a8f4d38a3c16d099e9f0c7b7b474c2f5e044af7c91949c04a234",
"uncles": [],
"withdrawals": [],
"withdrawalsRoot": "0x57f4414a70a4af5e1a97b5fd8b8c6c870c00e8d9dbc0fde0059ce46e2cd28e5b"
}
}