wallet_addEthereumChain

MetaMask

Creates a confirmation asking the user to add the specified chain to the wallet application. The caller must specify a chain ID and some chain metadata. The wallet application may refuse or accept the request. null is returned if the chain is added, and an error otherwise. Introduced by EIP-3085.

Params

(1)

1. AddEthereumChainParameter (required)

chainId

string

required

The chain ID as a 0x-prefixed hexadecimal string, per the eth_chainId method. MetaMask compares this chain ID value with the eth_chainId return value. If these values aren't identical, MetaMask rejects the request.

blockExplorerUrls

array[string]

(Optional) One or more URLs pointing to block explorer sites for the chain.

chainName

string

required

A human-readable name for the chain.

iconUrls

array[string<uri>]

(Optional) One or more URLs pointing to reasonably sized images that can be used to visually identify the chain. NOTE: MetaMask will not currently display these images. Values can still be included so that they are utilized if MetaMask incorporates them into the display of custom networks in the future.

nativeCurrency

NativeCurrency

required

Describes the native currency of the chain using the name, symbol, and decimals fields.

decimals

integer

required

A non-negative integer.

>= 0

name

string

A human-readable name.

symbol

string

required

A human-readable symbol.

rpcUrls

array[string<uri>]

required

One or more URLs pointing to RPC endpoints that can be used to communicate with the chain. At least one item is required, and only the first item is used.

>= 1 items

Result

(AddEthereumChainResult)

null

Errors

Code	Message
-32602	Expected null or array with at least one valid string HTTPS URL 'blockExplorerUrl'. Received: ${blockExplorerUrls}
-32602	Expected 0x-prefixed, unpadded, non-zero hexadecimal string 'chainId'. Received: ${chainId}
-32602	Invalid chain ID "${_chainId}": numerical value greater than max safe value. Received: ${chainId}
-32602	May not specify default MetaMask chain.
-32602	Expected 2-6 character string 'nativeCurrency.symbol'. Received: ${ticker}
-32602	nativeCurrency.symbol does not match currency symbol for a network the user already has added with the same chainId. Received: ${ticker}

Example

Request

await window.ethereum.request({
  "method": "wallet_addEthereumChain",
  "params": [
    {
      "chainId": "0x64",
      "chainName": "Gnosis",
      "rpcUrls": [
        "https://rpc.gnosischain.com"
      ],
      "iconUrls": [
        "https://xdaichain.com/fake/example/url/xdai.svg",
        "https://xdaichain.com/fake/example/url/xdai.png"
      ],
      "nativeCurrency": {
        "name": "XDAI",
        "symbol": "XDAI",
        "decimals": 18
      },
      "blockExplorerUrls": [
        "https://blockscout.com/poa/xdai/"
      ]
    }
  ]
});

Result

"null"