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The optimism API provides methods for interacting with Kona’s rollup state and configuration.

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optimism_outputAtBlock

Returns the output root at a specific block number, including the L2 block reference, withdrawal storage root, state root, and sync status.
ClientMethod invocation
RPC{"method": "optimism_outputAtBlock", "params": [blockNumber]}

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Parameters

  • blockNumber (BlockNumberOrTag): The block number to get the output for. Can be a number, “latest”, “earliest”, “pending”, “safe”, or “finalized”.

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Returns

OutputResponse - An object containing:
  • version (string): The output version hash
  • outputRoot (string): The output root hash
  • blockRef (L2BlockInfo): Reference to the L2 block
  • withdrawalStorageRoot (string): The withdrawal storage root
  • stateRoot (string): The state root
  • syncStatus (SyncStatus): The current sync status of the node

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Example

// > {"jsonrpc":"2.0","id":1,"method":"optimism_outputAtBlock","params":["latest"]}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "version": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "outputRoot": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "blockRef": {
      "hash": "0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890",
      "number": 12345,
      "parentHash": "0x9876543210fedcba9876543210fedcba9876543210fedcba9876543210fedcba",
      "timestamp": 1699123456,
      "l1Origin": {
        "hash": "0xfedcba0987654321fedcba0987654321fedcba0987654321fedcba0987654321",
        "number": 18123456
      },
      "sequenceNumber": 42
    },
    "withdrawalStorageRoot": "0x567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef1234",
    "stateRoot": "0xcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890ab",
    "syncStatus": {
      "current_l1": {
        "hash": "0x1111111111111111111111111111111111111111111111111111111111111111",
        "number": 18123456
      },
      "current_l1_finalized": {
        "hash": "0x2222222222222222222222222222222222222222222222222222222222222222",
        "number": 18123400
      },
      "head_l1": {
        "hash": "0x3333333333333333333333333333333333333333333333333333333333333333",
        "number": 18123460
      },
      "safe_l1": {
        "hash": "0x4444444444444444444444444444444444444444444444444444444444444444",
        "number": 18123450
      },
      "finalized_l1": {
        "hash": "0x5555555555555555555555555555555555555555555555555555555555555555",
        "number": 18123400
      },
      "unsafe_l2": {
        "hash": "0x6666666666666666666666666666666666666666666666666666666666666666",
        "number": 12350,
        "parentHash": "0x7777777777777777777777777777777777777777777777777777777777777777",
        "timestamp": 1699123500,
        "l1Origin": {
          "hash": "0x8888888888888888888888888888888888888888888888888888888888888888",
          "number": 18123460
        },
        "sequenceNumber": 47
      },
      "safe_l2": {
        "hash": "0x9999999999999999999999999999999999999999999999999999999999999999",
        "number": 12345,
        "parentHash": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
        "timestamp": 1699123456,
        "l1Origin": {
          "hash": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
          "number": 18123456
        },
        "sequenceNumber": 42
      },
      "finalized_l2": {
        "hash": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
        "number": 12340,
        "parentHash": "0xdddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
        "timestamp": 1699123400,
        "l1Origin": {
          "hash": "0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
          "number": 18123400
        },
        "sequenceNumber": 37
      },
      "cross_unsafe_l2": {
        "hash": "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
        "number": 12350,
        "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000001",
        "timestamp": 1699123500,
        "l1Origin": {
          "hash": "0x0000000000000000000000000000000000000000000000000000000000000002",
          "number": 18123460
        },
        "sequenceNumber": 47
      },
      "local_safe_l2": {
        "hash": "0x0000000000000000000000000000000000000000000000000000000000000003",
        "number": 12345,
        "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000004",
        "timestamp": 1699123456,
        "l1Origin": {
          "hash": "0x0000000000000000000000000000000000000000000000000000000000000005",
          "number": 18123456
        },
        "sequenceNumber": 42
      }
    }
  }
}

​
optimism_syncStatus

Returns the current synchronization status of the rollup node, including information about L1 and L2 block states.
ClientMethod invocation
RPC{"method": "optimism_syncStatus", "params": []}

​
Returns

SyncStatus - An object containing detailed sync information:
  • current_l1 (BlockInfo): The current L1 block that derivation is idled at
  • current_l1_finalized (BlockInfo): The current L1 finalized block (legacy/deprecated)
  • head_l1 (BlockInfo): The L1 head block reference
  • safe_l1 (BlockInfo): The L1 safe head block reference
  • finalized_l1 (BlockInfo): The finalized L1 block reference
  • unsafe_l2 (L2BlockInfo): The unsafe L2 block reference (absolute tip)
  • safe_l2 (L2BlockInfo): The safe L2 block reference (derived from L1)
  • finalized_l2 (L2BlockInfo): The finalized L2 block reference
  • cross_unsafe_l2 (L2BlockInfo): Cross-unsafe L2 block with verified cross-L2 dependencies
  • local_safe_l2 (L2BlockInfo): Local safe L2 block derived from L1, not yet cross-verified

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Example

// > {"jsonrpc":"2.0","id":1,"method":"optimism_syncStatus","params":[]}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "current_l1": {
      "hash": "0x1111111111111111111111111111111111111111111111111111111111111111",
      "number": 18123456
    },
    "current_l1_finalized": {
      "hash": "0x2222222222222222222222222222222222222222222222222222222222222222",
      "number": 18123400
    },
    "head_l1": {
      "hash": "0x3333333333333333333333333333333333333333333333333333333333333333",
      "number": 18123460
    },
    "safe_l1": {
      "hash": "0x4444444444444444444444444444444444444444444444444444444444444444",
      "number": 18123450
    },
    "finalized_l1": {
      "hash": "0x5555555555555555555555555555555555555555555555555555555555555555",
      "number": 18123400
    },
    "unsafe_l2": {
      "hash": "0x6666666666666666666666666666666666666666666666666666666666666666",
      "number": 12350,
      "parentHash": "0x7777777777777777777777777777777777777777777777777777777777777777",
      "timestamp": 1699123500,
      "l1Origin": {
        "hash": "0x8888888888888888888888888888888888888888888888888888888888888888",
        "number": 18123460
      },
      "sequenceNumber": 47
    },
    "safe_l2": {
      "hash": "0x9999999999999999999999999999999999999999999999999999999999999999",
      "number": 12345,
      "parentHash": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
      "timestamp": 1699123456,
      "l1Origin": {
        "hash": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
        "number": 18123456
      },
      "sequenceNumber": 42
    },
    "finalized_l2": {
      "hash": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
      "number": 12340,
      "parentHash": "0xdddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
      "timestamp": 1699123400,
      "l1Origin": {
        "hash": "0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
        "number": 18123400
      },
      "sequenceNumber": 37
    },
    "cross_unsafe_l2": {
      "hash": "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
      "number": 12350,
      "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000001",
      "timestamp": 1699123500,
      "l1Origin": {
        "hash": "0x0000000000000000000000000000000000000000000000000000000000000002",
        "number": 18123460
      },
      "sequenceNumber": 47
    },
    "local_safe_l2": {
      "hash": "0x0000000000000000000000000000000000000000000000000000000000000003",
      "number": 12345,
      "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000004",
      "timestamp": 1699123456,
      "l1Origin": {
        "hash": "0x0000000000000000000000000000000000000000000000000000000000000005",
        "number": 18123456
      },
      "sequenceNumber": 42
    }
  }
}

​
optimism_rollupConfig

Returns the rollup configuration parameters that define the rollup chain’s behavior and properties.
ClientMethod invocation
RPC{"method": "optimism_rollupConfig", "params": []}

​
Returns

RollupConfig - An object containing the complete rollup configuration:
  • genesis (ChainGenesis): The genesis state of the rollup
  • blockTime (number): The block time of the L2 in seconds
  • maxSequencerDrift (number): Maximum sequencer drift in seconds
  • seqWindowSize (number): The sequencer window size
  • channelTimeout (number): Number of L1 blocks between channel open/close
  • graniteChannelTimeout (number): Channel timeout after Granite hardfork
  • l1ChainId (number): The L1 chain ID
  • l2ChainId (number): The L2 chain ID
  • batchInboxAddress (string): L1 address where batches are sent
  • depositContractAddress (string): L1 address for deposits
  • l1SystemConfigAddress (string): L1 address for system config
  • protocolVersionsAddress (string): L1 address for protocol versions
  • Additional configuration fields for hardforks, fees, and interoperability

​
Example

// > {"jsonrpc":"2.0","id":1,"method":"optimism_rollupConfig","params":[]}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "genesis": {
      "l1": {
        "hash": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
        "number": 18000000
      },
      "l2": {
        "hash": "0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890",
        "number": 0,
        "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "timestamp": 1699000000,
        "l1Origin": {
          "hash": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
          "number": 18000000
        },
        "sequenceNumber": 0
      },
      "l2Time": 1699000000,
      "systemConfig": {
        "batcherAddr": "0x1234567890123456789012345678901234567890",
        "overhead": "0x00000000000000000000000000000000000000000000000000000000000000bc",
        "scalar": "0x00000000000000000000000000000000000000000000000000000000000f4240",
        "gasLimit": 30000000
      }
    },
    "blockTime": 2,
    "maxSequencerDrift": 600,
    "seqWindowSize": 3600,
    "channelTimeout": 300,
    "graniteChannelTimeout": 50,
    "l1ChainId": 1,
    "l2ChainId": 10,
    "batchInboxAddress": "0xff00000000000000000000000000000000000010",
    "depositContractAddress": "0xbEb5Fc579115071764c7423A4f12eDde41f106Ed",
    "l1SystemConfigAddress": "0x229047fed2591dbec1eF1118d64F7aF3dB9EB290",
    "protocolVersionsAddress": "0x8062AbC286f5e7D9428a0Ccb9AbD71e50d93b935",
    "superchainConfigAddress": "0x95703e0982140D16f8ebA6d158FccEde42f04a4C",
    "blobs_data": 1710374400,
    "interopMessageExpiryWindow": 3600,
    "chainOpConfig": {
      "canyon_denominator": 250,
      "canyon_elasticity": 6
    }
  }
}

​
optimism_version

Returns the software version of the Kona rollup node.
ClientMethod invocation
RPC{"method": "optimism_version", "params": []}

​
Returns

string - The version string of the Kona software (e.g., “0.1.0”)

​
Example

// > {"jsonrpc":"2.0","id":1,"method":"optimism_version","params":[]}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0.1.0"
}

​
Deprecated Methods

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optimism_safeHeadAtL1Block

This RPC endpoint is not supported in Kona. It was used to track the safe head for every L1 block, but this is no longer necessary post-interop. Calling this method will return a “Method not found” error.
ClientMethod invocation
RPC{"method": "optimism_safeHeadAtL1Block", "params": [blockNumber]}

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Returns

This method returns an error with code -32601 (Method not found).