> For the complete documentation index, see [llms.txt](/llms.txt).

# About the Snaps APIs

Snaps, dapps, and MetaMask can communicate with each other using the [Snaps API](#snaps-api), [Wallet API](#wallet-api), and [custom JSON-RPC APIs](#custom-json-rpc-apis).

## Snaps API[​](#snaps-api "Direct link to Snaps API")

Snaps can access the global object `snap`, which has one method: `request`. You can use this object to make [Snaps API](/snaps/reference/snaps-api/) requests. These API methods allow Snaps to extend or modify the functionality of MetaMask.

To call each method (except the [interactive UI methods](/snaps/features/custom-ui/interactive-ui/)), you must first [request permission](/snaps/how-to/request-permissions/) in the Snap manifest file. For example, to call [snap_notify](/snaps/reference/snaps-api/snap%5Fnotify/), first request the `snap_notify` permission:

snap.manifest.json

```
"initialPermissions": {
  "snap_notify": {}
}

```

Your Snap can then call `snap_notify` in its source code:

index.ts

```
await snap.request({
  method: 'snap_notify',
  params: {
    type: 'inApp',
    message: 'Hello, world!',
  },
})

```

## Wallet API[​](#wallet-api "Direct link to Wallet API")

### Dapp requests[​](#dapp-requests "Direct link to Dapp requests")

Dapps can install and communicate with Snaps using the following Wallet API methods for Snaps:

- [wallet_getSnaps](/snaps/reference/snaps-api/wallet%5Fgetsnaps/) - Gets the dapp's permitted Snaps.
- [wallet_requestSnaps](/snaps/reference/snaps-api/wallet%5Frequestsnaps/) - Requests permission to communicate with the specified Snaps.
- [wallet_snap](/snaps/reference/snaps-api/wallet%5Fsnap/) - (Restricted) Calls the specified custom JSON-RPC API method of the specified Snap.
- [wallet_invokeSnap](/snaps/reference/snaps-api/wallet%5Finvokesnap/) - (Restricted) Synonymous with `wallet_snap`.

A dapp must first [request permission](/snaps/how-to/request-permissions/#request-permissions-from-a-dapp)to communicate with a Snap using `wallet_requestSnaps`. The dapp can then call `wallet_snap` or `wallet_invokeSnap` on the permitted Snap. For example, to call `wallet_snap`:

index.js

```
// Request permission to connect to the Snap.
await window.ethereum.request({
  method: 'wallet_requestSnaps',
  params: {
    'npm:hello-snap': {},
  },
})

// Call the "hello" method of the Snap using wallet_snap.
const response = await window.ethereum.request({
  method: 'wallet_snap',
  params: {
    snapId: 'npm:hello-snap',
    request: {
      method: 'hello',
    },
  },
})

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

```

### Snap requests[​](#snap-requests "Direct link to Snap requests")

Snaps can also call some Wallet JSON-RPC API methods using the `ethereum` global, which is an [EIP-1193](https://eips.ethereum.org/EIPS/eip-1193) provider.

To expose `ethereum` to the Snap execution environment, a Snap must first request the [endowment:ethereum-provider](/snaps/reference/permissions/#endowmentethereum-provider) permission. For example, to call [eth_requestAccounts](/metamask-connect/evm/reference/json-rpc-api/), first request the required permission:

snap.manifest.json

```
"initialPermissions": {
  "endowment:ethereum-provider": {}
}

```

Your Snap can then call `eth_requestAccounts` in its source code:

index.ts

```
await ethereum.request({ method: 'eth_requestAccounts' })

```

The `ethereum` global available to Snaps has fewer capabilities than `window.ethereum` for dapps. Snaps can only use it to make read requests, not to write to the blockchain or initiate transactions. Snaps can call all Wallet JSON-RPC API methods **except** the following:

- `wallet_requestPermissions`
- `wallet_revokePermissions`
- `wallet_addEthereumChain`
- `wallet_switchEthereumChain`
- `wallet_watchAsset`
- `wallet_registerOnboarding`
- `wallet_scanQRCode`
- `eth_sendTransaction`
- `eth_decrypt`
- `eth_getEncryptionPublicKey`

## Custom JSON-RPC APIs[​](#custom-json-rpc-apis "Direct link to Custom JSON-RPC APIs")

Snaps can implement their own custom JSON-RPC APIs to communicate with dapps and other Snaps. To do so, a Snap must expose the [onRpcRequest](/snaps/reference/entry-points/#onrpcrequest) entry point and request the [endowment:rpc](/snaps/reference/permissions/#endowmentrpc) permission.

The Snap's custom API is entirely up to you, as long as it's a valid [JSON-RPC](https://www.jsonrpc.org/specification) API.

note

If your Snap can do something useful without receiving and responding to JSON-RPC requests, such as providing [transaction insights](/snaps/reference/entry-points/#ontransaction), you do not need to implement a custom API. However, if you want to do something such as manage the user's keys for a particular protocol and create a dapp that sends transactions for that protocol via your Snap, you must implement a custom API.

For example, to create a simple Snap with a custom API, first request the `endowment:rpc` permission. Set `dapps` to `true` to enable dapps to make JSON-RPC requests.

snap.manifest.json

```
"initialPermissions": {
  "endowment:rpc": {
    "dapps": true
  }
}

```

Your Snap can then implement and expose a custom API using the `onRpcRequest` function:

index.ts

```
module.exports.onRpcRequest = async ({ origin, request }) => {
  switch (request.method) {
    // Expose a "hello" JSON-RPC method to dapps.
    case 'hello':
      return 'world!'

    default:
      throw new Error('Method not found.')
  }
}

```

A dapp can then install the Snap and call the exposed method:

index.js

```
// Request permission to connect to the Snap.
// 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!"

```