Chain

Ethereum chain configuration with network metadata

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Run Chain examples in the interactive playground

Chain

Ethereum chain configuration objects with network metadata, RPC endpoints, and explorer information.

Learn about chain IDs, replay attack prevention, and network identification in the Fundamentals guide.

Overview

Branded type representing Ethereum chain configurations. Provides chain constants, metadata, and lookup utilities for Ethereum networks. Zero-overhead design supports both tree-shakeable namespace methods and class instances.

Quick Start

Types

class Chain

class Chain {
  // Constructors (→ /primitives/chain/constructors)
  static from(chain: Chain): Chain
  static fromId(id: number): Chain | undefined

  // Lookup (→ /primitives/chain/chain-lookup)
  static byId: Record<number, Chain>
}

Source: Chain.js:14-36

type Chain

export interface Chain {
  name: string
  chain: string
  chainId: number
  networkId?: number
  shortName: string
  rpc: string[]
  nativeCurrency: NativeCurrency
  infoURL?: string
  explorers?: Explorer[]
  [key: string]: any
}

export interface NativeCurrency {
  name: string
  symbol: string
  decimals: number
  [key: string]: any
}

export interface Explorer {
  name: string
  url: string
  standard?: string
  [key: string]: any
}

Chain configuration object extending from @tevm/chains. Provides complete chain metadata including network name, chain ID, RPC endpoints, native currency details, and block explorer URLs.

Source: ChainType.ts:1

Chain Constants

Chain objects imported from @tevm/chains:

import {
  // Mainnets
  flr14,
  quai9,
  injective1776,
  ronin2020,
  moca2288,

  // Popular networks (via chain ID)
  // Use Chain.fromId(id) or Chain.byId[id]
} from '@tevm/chains'

// Access chain metadata
console.log(quai9.name)          // "Quai Mainnet"
console.log(quai9.chainId)       // 9
console.log(quai9.nativeCurrency.symbol) // "QUAI"

// Use with Chain constructor
const chain = Chain(quai9)

Available constants:

• 800+ chain configurations from @tevm/chains
• Includes testnets, mainnets, L2s, and sidechains
• Each constant includes full metadata (RPC, explorer, currency)

See @tevm/chains documentation for complete list.

API Methods

Core Operations

• fundamentals - Learn chain IDs, replay attack prevention, and network identification
• constructors - Create Chain instances from chain objects and chain IDs
• chain-lookup - Look up chains by ID using fromId() and byId record
• metadata - Access chain properties: name, chainId, RPC, explorers, currency

Advanced Features

• branded-chain - Tree-shakeable functional API for minimal bundle size
• network-comparison - Compare gas fees, costs, and characteristics across networks

Chain is a lightweight wrapper around plain JavaScript objects from @tevm/chains. The Chain class adds prototype methods while keeping the underlying data structure simple and serializable.

Related Types

• Chain (Effect) - Effect.ts integration with Schema validation

Address

Ethereum address type for contract and account addresses.

View Address →

Branded Types

Zero-overhead type branding pattern used throughout primitives.

View Branded Types →

Denomination

Wei, Gwei, and Ether types with currency conversions.

View Denomination →

FeeMarket

EIP-1559 gas pricing with base and priority fees.

View FeeMarket →

Hardfork

Ethereum network upgrades and protocol versions.

View Hardfork →

Transaction

Transaction creation and signing across networks.

View Transaction →