Fork version by state ID

The /eth/v1/beacon/states/{state_id}/fork method provides information about the fork version and epoch associated with a given state. This endpoint is essential for understanding the current and previous fork versions that the Beacon state has undergone and the epoch at which the latest fork has occurred.


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  • state_id โ€” the identifier for the state for which fork information is being requested. The state_id can be:
    • head โ€” represents the latest canonical state in the node's view.
    • genesis โ€” refers to the state at the genesis or the start of the Beacon Chain.
    • finalized โ€” the state that is finalized and accepted by the network with minimal likelihood of reorganization.
    • justified โ€” a state that has recently achieved justification, which is a precursor to finalization in the Ethereum 2.0 proof of stake mechanism.
    • <slot> โ€” specific slot number in the Ethereum 2.0 protocol timeline.
    • <hex encoded stateroot with 0x prefix> โ€” the specific state root of interest, encoded in hexadecimal format.


The response is an object containing the following fields:

  • execution_optimistic โ€” a boolean indicating if the response is based on an unverified execution payload. If trueimplies that the payload might be invalidated later. The absence of this field implies a default value of false.
  • finalized โ€” a boolean indicating if the response pertains to the finalized history of the chain. If absent, it suggests the need for additional calls to determine the epochโ€™s relation to the finalized checkpoint.
  • data โ€” an object containing:
    • previous_version โ€” a hexadecimal string representing the fork version of the state before the current fork.
    • current_version โ€” a hexadecimal string indicating the fork version of the current state.
    • epoch โ€” the epoch number at which the current version was adopted.
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