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Access a user's MetaMask provider

Use the metamask-extension-provider module to access a user's MetaMask provider from other web extensions.

The account provided by this provider is the user's MetaMask account. When sending signing requests to this provider, MetaMask prompts the user to sign with their accounts.

This module works in Chrome and Firefox.

Install metamask-extension-provider using the following command:

npm install metamask-extension-provider -s
tip

You can use a bundler such as Browserify with metamask-extension-provider.

To use the module, add something like the following to your project script:

const createMetaMaskProvider = require('metamask-extension-provider');

const provider = createMetaMaskProvider();

provider.on('error', (error) => {
  // Failed to connect to MetaMask, fallback logic.
});

To add support for an additional browser, add MetaMask's extension ID for that browser's store to the configuration file. For example:

{
  "CHROME_ID": "nkbihfbeogaeaoehlefnkodbefgpgknn",
  "FIREFOX_ID": "webextension@metamask.io"
}

Run the example​

The sample-extension directory contains an example web extension implementation. You can easily add it to Chrome or Firefox Developer Edition.

You must have Browserify installed (npm i -g browserify) to edit the example.

You can edit the sample file sample-extension/index.js and rebuild the file using npm run buildSample.

You must edit the method getMetaMaskId() to return your local development MetaMask instance's ID. You can get that from your MetaMask console using chrome.runtime.id.