mega_outputAtBlock

mega_outputAtBlock JSON-RPC reference for MegaETH.

Summary

Returns the output root at a given block.

The public MegaETH endpoint supports this method. The standard, node, and gateway layers below identify behavior that differs from a generic Ethereum endpoint.

Parameters

blockNumber Quantity REQUIRED

Concrete hex block number; block tags such as latest are not accepted.

Result

• version Hash32, optional

  Output version. Fresh upstream responses can include it, while the gateway's cached projection currently omits it.
• outputRoot Hash32

  Output commitment.
• blockRef object

  Block reference; see fields below.

  • hash Hash32

    Block hash.
  • number number

    Block number (JSON number).
  • parentHash Hash32

    Parent block hash.
  • timestamp number

    Block timestamp (JSON number).
  • l1origin object

    L1 origin with hash and number.
  • sequenceNumber number

    Sequence number.
• withdrawalStorageRoot Hash32

  Withdrawal storage root.
• stateRoot Hash32

  State root.
• syncStatus object

  Backend sync-status snapshot.

Comparison with Ethereum Standard JSON-RPC

Ethereum Standard

mega_outputAtBlock is not part of the core Ethereum execution JSON-RPC API. It is a MegaETH extension.

MegaETH Node Behavior

The current MegaETH execution node's related native method is mega_optimismOutputAtBlock, which forwards a concrete block number to the OP node's optimism_outputAtBlock endpoint. The public mega_outputAtBlock spelling is a gateway-facing compatibility name.

MegaETH Public Gateway

The gateway rewrites this method to optimism_outputAtBlock and routes it to the OP-node pool. It caches stable output data for 30 minutes but refreshes the embedded synchronization status on a 1-second cadence. Its cached projection omits the upstream version field, so callers must tolerate version being present on a fresh response and absent on a cache hit.

Errors

The | Scope | column distinguishes method failures from gateway policy errors.

Code	Scope	Message	When it happens
-32602	Request	Invalid params	Missing block number, wrong parameter count, or block tag instead of hex block number
-32603	Method	Internal error	Backend cannot produce output data for the requested block
-32005	Transport/policy	Rate limit exceeded	The caller exceeds the public gateway's simple read budget.
-32099	Transport/policy	Payload too large	The request body exceeds the 128 KiB public endpoint limit.

See also Error Codes.

Examples

Endpoint: https://mainnet.megaeth.com/rpc

Capture date: July 27, 2026

Outcome: success

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "mega_outputAtBlock",
  "params": ["0x154de48"]
}

The captured response below is abridged; syncStatus contains additional L1 and L2 progress fields.

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "outputRoot": "0xf90851c88ec4adfe04b03f33beab99bbabbd73fc474ab7b3a8fa109a3913f047",
    "blockRef": {
      "hash": "0xce5344be15fecbe70574c97e57626f79a0816e8ebfc37a53ad535e82dd2def56",
      "number": 22339144,
      "parentHash": "0x85f2e75f7be8967a319af7de35275ad257150f80ae243b97f07b45332d3476a1",
      "timestamp": 1785136155,
      "l1origin": {
        "hash": "0xf79fbbd55e49baaff2f61e027b424b1b5b1ef7cd58bd7d664eb39947352b2f73",
        "number": 25622475
      },
      "sequenceNumber": 137
    },
    "syncStatus": {
      "head_l1": {
        "number": 25622556
      }
    },
    "withdrawalStorageRoot": "0x891f4462376be7ecac17a67a0ee5be7bc0c35979c182e5f7f19ebb2b1e320cc3",
    "stateRoot": "0x686f5150a2aec8f1b5ae15108288530860fa4157a9f39c71e55b0fa24783d506"
  }
}

Sources

• Spec: EIP-1474 for JSON-RPC framing and error conventions; this method is an extension or legacy compatibility method.
• Code: [email protected]:megaeth-labs/mega-reth.git @ ab60376631228edab3a6df180f295280bad26e93: crates/megaeth/rpc/src/mega.rs
• Code: [email protected]:megaeth-labs/mega-rpc.git @ 06aa35aa95d569c227cc25d2aa12834eb0458aa0: workers/src/processors/op-output-processor.ts
• Probe: MegaETH Mainnet public endpoint, July 27, 2026; response abridged to stable top-level fields