MetaMask is a premier non-custodial cryptocurrency wallet and browser extension, supporting Ethereum and EVM-compatible blockchains. It allows users to store, swap, and manage thousands of tokens and NFTs, access decentralized applications (dApps), and perform cross-chain bridging. Serving over 100 million users, it features a user-friendly interface, hardware wallet integration, and robust security through local key storage. Available on Chrome, Firefox, iOS, and Android.