Request permissions

Snaps must request permission to access certain powerful JavaScript globals or API methods. Dapps must also request permission to access certain API methods to communicate with Snaps.

Snaps and dapps follow the EIP-2255 wallet permissions specification.

Request permissions from a Snap

Snaps API methods

Request permission to call Snaps API methods in the initialPermissions field of the Snap manifest file. For example, to request to call snap_dialog, add the following to the manifest file:

snap.manifest.json

"initialPermissions": {
  "snap_dialog": {}
}

note

All Snaps API methods except the following interactive UI methods require requesting permission in the manifest file:

• snap_createInterface
• snap_getInterfaceState
• snap_updateInterface

Endowments

Endowments are a type of permission. Request endowments in the initialPermissions field of the Snap manifest file. See the Snaps permissions reference for the full list of endowments.

For example, to request the endowment:network-access permission, add the following to the manifest file:

snap.manifest.json

"initialPermissions": {
  "endowment:network-access": {}
}

Dynamic permissions

Dynamic permissions are not requested in the manifest file. Instead, your Snap can acquire dynamic permissions during its lifecycle.

For example, request permission to call the eth_accounts MetaMask JSON-RPC API method by calling eth_requestAccounts. See the eth_accounts dynamic permission for more information.

Request permissions from a dapp

Dapps that communicate with Snaps using wallet_snap and wallet_invokeSnap must request permission to do so by calling the wallet_requestSnaps MetaMask JSON-RPC API method.

The following example calls wallet_requestSnaps to request permission to connect to the hello-snap Snap, then calls wallet_invokeSnap to invoke the hello JSON-RPC method exposed by the Snap:

index.js

// If the Snap is not already installed, the user will be prompted to install it.
await window.ethereum.request({
  method: "wallet_requestSnaps",
  params: {
    // Assuming the Snap is published to npm using the package name "hello-snap".
    "npm:hello-snap": {},
  },
});

// Invoke the "hello" JSON-RPC method exposed by the Snap.
const response = await window.ethereum.request({
  method: "wallet_invokeSnap",
  params: { snapId: "npm:hello-snap", request: { method: "hello" } },
});

console.log(response); // "world!"

note

Learn more about implementing custom JSON-RPC APIs in a Snap.