WebMetamask® Chrome® Extension® | Getting started with MetaMask. Learn how to use the Metamask extension, a browser plugin that lets you store Ethereum and other Getting started with Metamask® Chrome® Extension®. Learn how to use the Metamask extension, a browser plugin that lets you store Ethereum and other tokens The WebMetamask® Chrome® Extension® | Getting started with MetaMask. Learn how to use the Metamask extension, a browser plugin that lets you store Ethereum and other MetaMask is an extension for accessing Ethereum enabled distributed applications, or "Dapps" in your browser! Watch an introductory video here. The extension injects the Ethereum web3 API into every Open your browser: Launch your preferred web browser. Go to the Metamask extension website: Type " MetaMask " into your search engine or directly navigate to metamask.io.