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Chain ID

A chain ID is a unique identifier that represents a blockchain network. We use it to distinguish different blockchain networks from each other and to ensure that transactions and messages are sent to the correct network. Evmos network follows the format of identifier_EIP155-version format.

Official Chain IDs

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NOTE: The latest Chain ID (i.e highest Version Number) is the latest version of the software and mainnet. Also note, that the following upgrades technically did not require a Chain ID change:

  • evmos_9001-1 -> evmos_9001-2
  • evmos_9000-3 -> evmos_9000-4

Mainnet

NameChain IDIdentifierEIP-155 NumberVersion NumberActive
Evmos 2evmos_9001-2evmos90012
Evmos 1evmos_9001-1evmos90011🚫

Testnet

NameChain IDIdentifierEIP-155 NumberVersion NumberActive
Evmos Public Testnetevmos_9000-4evmos90004
Evmos Public Testnetevmos_9000-3evmos90003🚫
Olympus Mons Incentivized Testnetevmos_9000-2evmos90002🚫
Arsia Mons Testnetevmos_9000-1evmos90001🚫
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You can also look up the EIP-155 Chain ID by referring to chainlist.org.

chainlist.org website

The Chain Identifier

Every chain must have a unique identifier or chain-id. Tendermint requires each application to define its own chain-id in the genesis.json fields. However, to comply with both EIP-155 and Cosmos standard for chain upgrades, Evmos-compatible chains must implement a special structure for their chain identifiers.

Structure

The Evmos Chain ID contains 3 main components

  • Identifier: Unstructured string that defines the name of the application.
  • EIP-155 Number: Immutable EIP-155 CHAIN_ID that defines the replay attack protection number.
  • Version Number: Is the version number (always positive) that the chain is currently running. This number MUST be incremented every time the chain is upgraded or forked to avoid network or consensus errors.

Format

The format for specifying and Evmos compatible chain-id in genesis is the following:

{identifier}_{EIP155}-{version}

The following table provides an example where the second row corresponds to an upgrade from the first one:

ChainIDIdentifierEIP-155 NumberVersion Number
evmos_9000-1evmos90001
evmos_9000-2evmos90002
............
evmos_9000-Nevmos9000N