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Detect MetaMask

Important

This page describes the legacy method of connecting to MetaMask using window.ethereum. We recommend connecting to MetaMask using EIP-6963 instead.

EIP-6963 introduces an alternative wallet detection mechanism to the window.ethereum injected provider. This alternative mechanism enables dapps to support wallet interoperability by discovering multiple injected wallet providers in a user's browser.

The presence of the MetaMask Ethereum provider object, window.ethereum, in a user's browser indicates an Ethereum user.

To demonstrate this, verify whether your browser is running MetaMask by copying and pasting the following code snippet into your browser's developer console:

if (typeof window.ethereum !== "undefined") {
  console.log("MetaMask is installed!");
}

You can use the @metamask/detect-provider module to detect the MetaMask Ethereum provider.

Steps​

1. Install @metamask/detect-provider​

Use npm to install @metamask/detect-provider in your project directory:

npm i @metamask/detect-provider

2. Detect the provider​

For example, the following code detects the provider using @metamask/detect-provider:

// This function detects most providers injected at window.ethereum.
import detectEthereumProvider from "@metamask/detect-provider";

// This returns the provider, or null if it wasn't detected.
const provider = await detectEthereumProvider();

if (provider) {
  // From now on, this should always be true:
  // provider === window.ethereum
  startApp(provider); // Initialize your dapp.
} else {
  console.log("Please install MetaMask!");
}

function startApp(provider) {
  // If the provider returned by detectEthereumProvider isn't the same as window.ethereum, something
  // is overwriting it – perhaps another wallet. See the "Connect to MetaMask" guide for detecting
  // and connecting to multiple wallets.
  if (provider !== window.ethereum) {
    console.error("Do you have multiple wallets installed?");
  }
  // Access the decentralized web!
}