> For the complete documentation index, see [llms.txt](https://docs.aeternity.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aeternity.com/developer-documentation/aepp-sdk-js/docs/guides/metamask-snap.md).

# Aeternity snap for MetaMask

This guide explains basic interactions on getting access to accounts on Aeternity snap for MetaMask using JS SDK.

## Prerequisite

Run the code from below you need:

* a MetaMask extension 12.2.4 or above installed in Chrome or Firefox browser;
* to setup an account in MetaMask (create a new one or restore by mnemonic phrase).

## Usage

Firstly, you need to create a factory of MetaMask accounts

```js
import { AccountMetamaskFactory } from '@aeternity/aepp-sdk';

const accountFactory = new AccountMetamaskFactory();
```

Using the factory, you can create instances of specific accounts by providing an index

```js
const account = await accountFactory.initialize(0);
console.log(account.address); // 'ak_2dA...'
console.log(await account.signTransaction('tx_...')); // 'tx_...' (with signature added)
```

The private key for the account would be derived in the MetaMask browser extension using the provided index and the mnemonic phrase it was initialized with. The private key won't leave the extension.

The complete examples of how to use it in browser can be found [here](https://github.com/aeternity/aepp-sdk-js/blob/1cd128798018d98bdd41eff9104442b44b385d46/examples/browser/aepp/src/components/ConnectMetamask.vue).

## Account persistence

Account can be persisted and restored by saving values of `index`, `address` properties

```js
import { AccountMetamask } from '@aeternity/aepp-sdk';

const accountIndex = accountToPersist.index;
const accountAddress = accountToPersist.address;

const accountFactory = new AccountMetamaskFactory();
const restoredAccount = new AccountMetamask(accountFactory.provider, accountIndex, accountAddress);
```

It can be used to remember accounts between app restarts.

## Account discovery

In addition to the above, it is possible to get access to a sequence of accounts that already have been used on chain. It is needed, for example, to restore the previously used accounts in case the user connects MetaMask to an app that doesn't aware of them.

```js
import { Node } from '@aeternity/aepp-sdk';

const node = new Node('https://testnet.aeternity.io');
const accounts = await accountFactory.discover(node);
console.log(accounts[0].address); // 'ak_2dA...'
```

## Error handling

If the user rejects an action (snap installation or connection, address retrieving or transaction/message signing) you will get an exception as a plain object with property `code` equals 4001, and `message` equals "User rejected the request.".

If the snap downgrade is requested, the code will be -32602.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.aeternity.com/developer-documentation/aepp-sdk-js/docs/guides/metamask-snap.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.