Network and RPC management

The extension ships the supported networks out of the box and lets users and dapps extend the EVM set.

The active network

The wallet has one active EVM network at a time. It determines where eth_* requests are sent and which chain id eth_chainId reports. Dapps switch it with wallet_switchEthereumChain; users switch it from the network picker. Either way, connected dapps get chainChanged.

The X and P-Chains are always addressable through the avalanche_* methods regardless of the active EVM network — chainAlias selects the chain per request.

Custom networks

Users can add any EVM network (chain id, RPC URL, symbol, explorer), and dapps can offer the same via wallet_addEthereumChain — Core validates that the RPC's reported chain id matches the request before accepting it.

Users can also override the RPC endpoint of an existing network — for example, pointing Avalanche C-Chain at their own node. Dapp developers should assume no particular RPC provider behind a user's wallet.

Testnet mode

One switch flips the whole wallet between mainnet and test variants — Fuji for Avalanche, plus Bitcoin and Ethereum test networks. Dapps can toggle it with avalanche_setDeveloperMode (behind a user prompt), and fund test accounts from the faucet.