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Multichain API

Flask Only
This feature is experimental and only available in MetaMask Flask, the canary distribution of MetaMask.

Dapps can call Multichain API methods to create and manage CAIP-25 connections with MetaMask. The API also provides events that wallets can send to dapps to notify them of onchain or connection changes.

See also

Methods​

wallet_createSession​

Creates a multichain connection with a wallet, authorizing that wallet with the specified set of scopes and properties. This method is defined in CAIP-25.

Parameters​

  • optionalScopes: object - Scopes that the wallet can support in order to be used with this dapp.
  • sessionProperties: object - Properties that the wallet can use to determine if the connection is valid.
  • requiredScopes: object - (Optional) Scopes that the wallet must support in order to be used with this dapp. We don't recommend using requiredScopes with MetaMask.

Returns​

The scopes and properties of the created connection.

Example​

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "wallet_createSession",
  "params": {
    "optionalScopes": {
      "eip155": {
        "references": ["1", "137"],
        "methods": ["eth_sendTransaction", "eth_signTransaction", "eth_sign", "get_balance", "personal_sign"],
        "notifications": ["accountsChanged", "chainChanged"]
      },
      "eip155:10": {
        "methods": ["get_balance"],
        "notifications": ["accountsChanged", "chainChanged"]
      },
      "eip155:0": {
        "methods": ["wallet_getPermissions", "wallet_creds_store", "wallet_creds_verify", "wallet_creds_issue", "wallet_creds_present"],
        "notifications": []
      },
      "eip155:42161": {
        "methods": ["eth_sendTransaction", "eth_signTransaction", "get_balance", "personal_sign"],
        "notifications": ["accountsChanged", "chainChanged"]
      }
    },
    "sessionProperties": {
      "expiry": "2022-12-24T17:07:31+00:00",
      "caip154-mandatory": "true"
    }
  }
}

wallet_getSession​

Gets the scopes and properties within the active connection. This method is defined in CAIP-312.

note

MetaMask doesn't support session IDs.

Parameters​

None.

Returns​

The scopes and properties of the connection.

Example​

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "wallet_getSession",
  "params": {}
}

wallet_invokeMethod​

Invokes the specified JSON-RPC API method on the specified network previously authorized to the dapp within a connection. This method is defined in CAIP-27.

note

MetaMask doesn't support session IDs.

Parameters​

  • scope: string - A CAIP-2 chain ID previously authorized to the dapp within a connection.
  • request: object - A request object containing:
    • method: string - The JSON-RPC API method to invoke, previously authorized to the dapp within a connection.
    • params: object - The RPC method parameters (can be empty).

Returns​

The response from the JSON-RPC method call.

Example​

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "wallet_invokeMethod",
  "params": {
    "scope": "eip155:1",
    "request": {
      "method": "eth_sendTransaction",
      "params": [
        {
          "to": "0x4B0897b0513FdBeEc7C469D9aF4fA6C0752aBea7",
          "from": "0xDeaDbeefdEAdbeefdEadbEEFdeadbeefDEADbEEF",
          "gas": "0x76c0",
          "value": "0x8ac7230489e80000",
          "data": "0x",
          "gasPrice": "0x4a817c800"
        }
      ]
    }
  }
}

wallet_revokeSession​

Revokes the active connection. This method is defined in CAIP-285.

note

MetaMask doesn't support session IDs.

Parameters​

None.

Returns​

true if the revocation was successful.

Example​

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "wallet_revokeSession",
  "params": {}
}

Events​

The Multichain API provides the following events that wallets can send to dapps to notify them of changes to a session.

wallet_notify​

Notifies the dapp of events or state changes related to a specific, previously authorized network. This event is defined in CAIP-319.

note

MetaMask doesn't support session IDs.

Parameters​

  • scope: string - A CAIP-2 chain ID previously authorized to the dapp within a connection.
  • notification: object - A notification object containing:
    • method: string - A JSON-RPC API notification method name previously authorized to the dapp within a connection.
    • params: object - The RPC notification method parameters.

Example​

{
  "jsonrpc": "2.0",
  "method": "wallet_notify",
  "params": {
    "scope": "eip155:1",
    "notification": {
      "method": "eth_subscription",
      "params": {
        "subscription": "0x12345678",
        "result": {
          "blockNumber": "0x1234",
          "transactionHash": "0x5678",
          "logIndex": "0x9abc"
        }
      }
    }
  }
}

wallet_sessionChanged​

Notifies the dapp of updates to the active connection's authorization scopes. This method is defined in CAIP-311.

note

MetaMask doesn't support session IDs.

Parameters​

sessionScopes: object - An object containing the full updated authorization scopes, each formatted according to CAIP-217.

Example​

{
  "jsonrpc": "2.0",
  "method": "wallet_sessionChanged",
  "params": {
    "sessionScopes": {
      "eip155:1": {
        "methods": ["eth_signTransaction", "eth_sendTransaction"],
        "notifications": ["message"],
        "accounts": ["eip155:1:0xabc123"]
      },
      "eip155:137": {
        "methods": ["eth_sendTransaction"],
        "notifications": [],
        "accounts": ["eip155:137:0xdef456"]
      }
    }
  }
}