Recently, we have received a number of suggestions from the community regarding support for new blockchains. Currently, MetaMask users are able to access the Ethereum mainnet, Ropsten, Kovan, and Rinkeby test networks through an easy network drop-down UI. While users are able to connect to other networks by specifying an RPC URL, it does require manual input and doesn’t persist if a user connects to a different custom RPC.

Because MetaMask is able to support some custom networks, various teams working on Ethereum RPC compatible chains have requested that MetaMask add menu options to gain easy and automatic access to their own networks in the network selection drop-down. This would be an easy UI implementation, but the politics of maintaining a comprehensive list of blockchains would quickly distract us from iterating on the core product for our users. Rather than maintaining a list of networks, we are more interested in pursuing a generalized solution that allows users to opt into the networks that they prefer, without involving the MetaMask team! Fortunately, the path for this generalized solution is already being paved:

In the pursuit of improved privacy and security, the MetaMask team has suggested EIP 1102 as a way to make web3 browser users undetectable while browsing the web, until a user deliberately reveals themselves. This initial sign-in API lays the groundwork for other sign-in options, including different accounts on different sites, and eventually even specific networks per application.